Quantum dots, a composition or composite including the same, and an electronic device including the same

ABSTRACT

A quantum dot including a first ligand and a second ligand on a surface of the quantum dot, a composition or composite including the same, and a device including the same. The first ligand includes a compound represented by Chemical Formula 1 and the second ligand includes a compound represented by Chemical Formula 2: 
       MA n   Chemical Formula 1
         wherein M, n, and A are the same as defined in the specification; and       

     
       
         
         
             
             
         
       
         
         
           
             wherein, 
             R 1 , L 1 , Y 1 , R, k1, and k2 are the same as defined in the specification.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of application Ser. No.15/820,781, filed Nov. 22, 2017, which claims priority to Korean PatentApplications Nos. 10-2016-0158704 and 10-2016-0174971, filed in theKorean Intellectual Property Office on Nov. 25, 2016 and Dec. 20, 2016,respectively, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which are both incorporated herein in theirentirety by reference.

BACKGROUND 1. Field

Quantum dots, a composition or composite including the same, and adevice including the same are disclosed.

2. Description of the Related Art

Quantum dots (e.g., nano-sized semiconductor nanocrystals) havingdifferent energy bandgaps may be obtained by controlling their sizes andcompositions. Such quantum dots may emit light having variouswavelengths. In a colloidal synthesis, organic materials such as adispersing agent or a solvent may coordinate, e.g., be bound, to asurface of the semiconductor during the growth thereof. As a result,quantum dots having a uniformly controlled size and showing desirableluminous properties and stabilities may be prepared.

However, the luminous properties of the quantum dots are susceptible tothe external environment. Thus, the quantum dots are mixed with (e.g.,dispersed in) a solid state matrix (e.g., a polymer matrix) to form aquantum dot polymer composite, which is then applied to variouselectronic devices such as different display devices and lightingdevices. The mixing of the quantum dot or the preparation processes ofthe device including the same may involve some processes such as aheat-treatment that may adversely affect the inherent luminousproperties of the quantum dots. Thus, there remains a need to develop atechnology for mixing a quantum dot into a medium or fabricating adevice including the same without causing deterioration of inherentproperties of the quantum dots.

SUMMARY

An embodiment is related to a composition for preparing a quantum dotpolymer composite capable of achieving improved process stability and toa quantum dot polymer composite prepared therefrom.

An embodiment provides an electronic device including the quantumdot-polymer composite.

In an embodiment, a quantum dot includes a semiconductor nanocrystalparticle, and a ligand bound to a surface of the semiconductornanocrystal particle, wherein the ligand includes a first ligandincluding (or derived from) a compound represented by Chemical Formula 1and a second ligand including (or derived from) a compound representedby Chemical Formula 2:

MA_(n)  Chemical Formula 1

wherein M is Mg, Ca, Sc, Sn, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr,Y, Zr, Nb, Mo, Cd, In, Ba, Au, Hg, or Tl, n is determined depending onthe valency of the M and is an integer of greater than or equal to 2,each A is the same or different, and is independently a C1 to C10organic group, a halogen, or a combination thereof.

wherein,

R¹ is hydrogen, a substituted or unsubstituted C1 to C40 (or C1 to C30)linear or branched alkyl group, a C2 to C40 (or C1 to C30) linear orbranched alkenyl group, a substituted or unsubstituted C6 to C30 arylgroup, a substituted or unsubstituted C7 to C30 arylalkyl group, asubstituted or unsubstituted C3 to C30 heteroaryl group, a substitutedor unsubstituted C4 to C30 heteroarylalkyl group, a substituted orunsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstitutedC2 to C30 heterocycloalkyl group, a C1 to C10 alkoxy group, a hydroxygroup, —NH₂, a substituted or unsubstituted C1 to C30 amine group(—NRR′, wherein R and R′ are the same or different, and areindependently hydrogen or a C1 to C30 linear or branched alkyl group,and provided that R and R′ are not hydrogen simultaneously), anisocyanate group, a halogen, —ROR′ (wherein R is a substituted orunsubstituted C1 to C20 alkylene group and R′ is hydrogen or a C1 to C20linear or branched alkyl group), an acyl halide group (—RC(═O)X, whereinR is a substituted or unsubstituted C1 to C20 alkylene group and X is ahalogen), —C(═O)OR′ (wherein R′ is hydrogen or a C1 to C20 linear orbranched alkyl group), —CN, —C(═O)NRR′ (wherein R and R′ are the same ordifferent, and are independently hydrogen or a C1 to C20 linear orbranched alkyl group), —C(═O)ONRR′ (wherein R and R′ are the same ordifferent, and are independently hydrogen or a C1 to C20 linear orbranched alkyl group) or a combination thereof,

L₁ is a carbon atom, a nitrogen atom, a substituted or unsubstituted C1to C30 alkylene group, a substituted or unsubstituted C2 to C30alkenylene group, a substituted or unsubstituted C3 to C30 cycloalkylenegroup, a substituted or unsubstituted C3 to C30 heterocycloalkylenegroup, a substituted or unsubstituted C6 to C30 arylene group, asubstituted or unsubstituted C3 to C30 heteroarylene group, or asubstituted or unsubstituted C2 to C30 alkylene group or a substitutedor unsubstituted C3 to C30 alkenylene group having at least onemethylene (—CH₂—) replaced with sulfonyl (—S(═O)₂—), carbonyl (—C(═O)—),ether (—O—), sulfide (—S—), sulfoxide (—S(═O)—), ester (—C(═O)O—), amide(—C(═O)NR—) (wherein R is hydrogen or a C1 to C10 alkyl group), or acombination thereof,

Y₁ is a single bond, —C(═S)—, a substituted or unsubstituted C1 to C30alkylene group, a substituted or unsubstituted C2 to C30 alkenylenegroup, or a C1 to C30 alkylene group or a C2 to C30 alkenylene groupwherein at least one methylene (—CH₂—) is replaced by sulfonyl(—S(═O)₂—), carbonyl (—C(═O)—), ether (—O—), sulfide (—S—), sulfoxide(—S(═O)—), ester (—C(═O)O—), amide (—C(═O)NR—) (wherein R is hydrogen ora C1 to C10 linear or branched alkyl group), imine (—NR—) (wherein R ishydrogen or a C1 to C10 linear or branched alkyl group), or acombination thereof,

R is hydrogen or a monovalent metal (e.g., an alkali metal such assodium);

k1 is 0 or an integer of 1 or more,

k2 is 1 or 2 wherein when the k2 is 2, the Y₁ is a single bond and thetwo SR moieties are bonded to adjacent two carbon atoms in the L₁moiety, respectively, and

provided that a sum of k1 and k2 does not exceed the valence of L₁.

The semiconductor nanocrystal particle may include a Group II-VIcompound, a Group III-V compound, a Group IV-VI compound, a Group IVelement or compound, a Group compound, a Group I-II-IV-VI compound, or acombination thereof.

The semiconductor nanocrystal particle may include a core including afirst semiconductor nanocrystal and a shell disposed on the core andincluding a second semiconductor nanocrystal.

The A of Chemical Formula 1 may include a C1 (e.g., C2) to C5 organicfunctional group

The A of Chemical Formula 1 may include a C2 to C5 hydrocarbyl group,RCOO— or ROCO— (wherein R is a C1 to C4 hydrocarbyl group), a halogen(e.g., a chlorine, bromine, or iodine), or a combination thereof.

The first ligand may include a metal that is a metal that is the same asa metal present on the surface of the quantum dot.

The first ligand may include an organic metal salt, a halogenated metal,a hydrocarbyl metal, a hydrocarbyl metal halide, a metal (meth)acrylate,a metal dialkyldithiocarbamate, or a combination thereof.

The first ligand may include indium chloride, cadmium chloride, aluminumchloride, iron chloride, manganese chloride, diethyl zinc, dipropylzinc, triethyl aluminum, tributyl aluminum, a zinc carboxylate (e.g., azinc acetate, a zinc propionate, a zinc butyrate, or the like), a zinc(meth)acrylate, a zinc chloride, indium acetate, or a combinationthereof.

The second ligand may include a compound represented by Chemical Formula2-1, Chemical Formula 2-2, or Chemical Formula 2-3:

R^(a)-L-(CRR)_(n)SM  Chemical Formula 2-1

RRNCSSM  Chemical Formula 2-3

wherein

R^(a) includes a substituted or unsubstituted C1 to C24 alkyl group, asubstituted or unsubstituted C2 to C24 alkenyl group, and a substitutedor unsubstituted C6 to C20 aryl group, R is the same or different, andis each independently hydrogen or a substituted or unsubstituted C1 toC24 alkyl group, n is an integer of 0 to 15, L is a direct bond, asulfonyl (—S(═O)₂—), carbonyl (—C(═O)—), ether group (—O—), sulfidegroup (—S—), sulfoxide group (—S(═O)—), ester group (—C(═O)O—), amidegroup (—C(═O)NR—) (wherein R is hydrogen or a C1 to C10 alkyl group), asubstituted or a unsubstituted C1 to C10 alkylene, a C2 to C10alkenylene, or a combination thereof, and M is hydrogen, lithium,sodium, potassium, or a combination thereof.

The second ligand may include a substituted or unsubstituted C1 to C40alkyl thiol compound, a C2 to C40 mercapto carboxylic acid compound, aC2 to C40 mercapto carboxylic acid alkyl ester compound, adithiocarbamate compound having a C1 to C40 alkyl group, or acombination thereof.

The second ligand may include butanethiol, pentanethiol, hexanethiol,heptanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol,dodecanethiol, octadecanethiol, 2-(2-methoxyethoxy)ethanethiol,3-methoxybutyl 3-mercaptopropionate, 3-methoxybutyl mercaptoacetate,thioglycolic acid, 3-mercaptopropionic acid, thiopronine (sulfhydrylacylated derivative of glycine), 2-mercaptopropionic acid, 2-mercaptopropionate, 2-mercaptoethanol, cysteamine, 1-thioglycerol,mercaptosuccinic acid, L-cysteine, dihydrolipoic acid,2-(dimethylamino)ethanethiol, 5-mercaptomethyl tetrazole,2,3-dimercapto-1-propanol glutathione, m(PEG)-SH, di(C1 to C30alkyl)dithiocarbamic acid or a metal salt thereof (e.g., di(C1 to C30alkyl)dithiocarbamate such as diethyldithiocarbamate), or a combinationthereof.

The second ligand does not include carboxylic acid moiety.

The quantum dot may have a 5% weight loss temperature of less than orequal to about 400° C. as determined by a thermogravimetric analysis.

In some embodiments, a composition includes:

the aforementioned quantum dot (e.g., a plurality of the aforementionedquantum dots);

a binder polymer;

a polymerizable (e.g., photopolymerizable) monomer having acarbon-carbon double bond; and

a photoinitiator.

The binder polymer may include a carboxylic acid group (—COOH).

The binder polymer includes

-   -   a copolymer of a monomer combination including a first monomer        having a carboxylic acid group and a carbon-carbon double bond,        a second monomer having a carbon-carbon double bond and a        hydrophobic moiety and not having a carboxylic acid group, and        optionally, a third monomer having a carbon-carbon double bond        and a hydrophilic moiety and not having a carboxylic acid group;    -   a multiple aromatic ring-containing polymer including a        carboxylic acid group and having a backbone structure in a main        chain, wherein the backbone structure includes a quaternary        carbon atom, which is a part of a cyclic group, and two aromatic        rings bound to the quaternary carbon atom; or    -   a combination thereof.

The binder polymer may have an acid value of greater than or equal toabout 50 milligrams of KOH per gram of the polymer.

The binder polymer may have an acid value of less than or equal to about250 milligrams of KOH per gram of the polymer.

The copolymer may include a first repeating unit derived from the firstmonomer, a second repeating unit derived from the second monomer, andoptionally a third repeating unit derived from the third monomer.

The first repeating unit may include a unit represented by ChemicalFormula 3-1, a unit represented by Chemical Formula 3-2, or acombination thereof:

wherein

R¹ is hydrogen, a C1 to C3 alkyl group, or —(CH₂)_(n)—COOH (wherein n is0 to 2),

R² is hydrogen, a C1 to C3 alkyl group, or —COOH,

L is a single bond, a divalent C1 to C15 aliphatic hydrocarbon group, adivalent C6 to C30 aromatic hydrocarbon group, a divalent C3 to C30alicyclic hydrocarbon group, or a divalent C1 to C15 aliphatichydrocarbon group substituted with a C6 to C30 aromatic hydrocarbongroup or a C3 to C30 alicyclic hydrocarbon group, and

* indicates a portion linked to an adjacent atom;

wherein

R¹ is hydrogen, a C1 to C3 alkyl group, or —(CH₂)_(n)—COOH (wherein n is0 to 2),

R² is hydrogen or a C1 to C3 alkyl group,

L is a divalent C1 to C15 alkylene group, a divalent C1 to C15 alkylenegroup wherein at least one methylene group is substituted with —C(═O)—,—O—, or —C(═O)O—, a divalent C6 to C30 aromatic hydrocarbon group, adivalent C3 to C30 alicyclic hydrocarbon group, or a divalent C1 to C15aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

n is an integer of 1 to 3, and

* indicates a portion linked to an adjacent atom.

The second repeating unit may include a unit represented by ChemicalFormula 4-1, a unit represented by Chemical Formula 4-2, a unitrepresented by Chemical Formula 4-3, a unit represented by ChemicalFormula 4-4, or a combination thereof:

wherein

R¹ is hydrogen or a C1 to C3 alkyl group,

R² is a C1 to C15 aliphatic hydrocarbon group, a C6 to C30 aromatichydrocarbon group, a C3 to C30 alicyclic hydrocarbon group, or a C1 toC15 aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

R³ is hydrogen or a C1 to C3 alkyl group, and

* indicates a portion linked to an adjacent atom;

wherein

R¹ is hydrogen or a C1 to C3 alkyl group,

L is a divalent C1 to C15 alkylene group, a divalent C1 to C15 alkylenegroup wherein at least one methylene group is substituted with —C(═O)—,—O—, or —C(═O)O—, a divalent C6 to C30 aromatic hydrocarbon group, adivalent C3 to C30 alicyclic hydrocarbon group, or a divalent C1 to C15aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

R² is a C1 to C15 aliphatic hydrocarbon group, a C6 to C30 aromatichydrocarbon group, a C3 to C30 alicyclic hydrocarbon group, or a C1 toC15 aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

R³ is hydrogen or a C1 to C3 alkyl group,

n is an integer of 1 to 3, and

* indicates a portion linked to an adjacent atom;

wherein

each of R¹ and R² is independently hydrogen or a C1 to C3 alkyl group,

Ar is a substituted or unsubstituted C6 to C30 aromatic hydrocarbongroup or a substituted or unsubstituted C3 to C30 alicyclic hydrocarbongroup, and

* indicates a portion linked to an adjacent atom;

wherein

R¹ is hydrogen or a C1 to C3 alkyl group,

R² is a C1 to C15 aliphatic hydrocarbon group, a C6 to C30 aromatichydrocarbon group, a C3 to C30 alicyclic hydrocarbon group, or a C1 toC15 aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

R³ is hydrogen or a C1 to C3 alkyl group, and

* indicates a portion linked to an adjacent atom.

The third repeating unit may be represented by Chemical Formula 5:

wherein

each of R¹ and IV is independently hydrogen or a C1 to C3 alkyl group,

L is a divalent C1 to C15 alkylene group, a divalent C1 to C15 alkylenegroup wherein at least one methylene group is substituted with —C(═O)—,—O—, or —C(═O)O—, a divalent C6 to C30 aromatic hydrocarbon group, adivalent C3 to C30 alicyclic hydrocarbon group, or a divalent C1 to C15aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

Z is a hydroxyl group (—OH), a mercapto group (—SH), or an amino group(—NHR, wherein R is hydrogen or a C1 to C5 alkyl group), and

* indicates a portion linked to an adjacent atom.

The multiple aromatic ring-containing polymer may include the backbonestructure including a unit represented by Chemical Formula A:

wherein

* indicates a portion that is linked to an adjacent atom of the mainchain of the binder,

Z¹ is a linking moiety represented by any one of Chemical Formulae A-1to A-6, and in Chemical Formulae A-1 to A-6, * indicates a portion thatis linked to the aromatic ring:

wherein R^(a) is hydrogen, an ethyl group, C₂H₄Cl, C₂H₄OH, CH₂CH═CH₂, ora phenyl group,

The composition may further include a thiol compound that is representedby Chemical Formula 6 and having a thiol group at its end terminals:

wherein,

R¹ is hydrogen, a substituted or unsubstituted C1 to C30 linear orbranched alkyl group, a C2 to C30 linear or branched alkenyl group, asubstituted or unsubstituted C6 to C30 aryl group, a substituted orunsubstituted C7 to C30 arylalkyl group, a substituted or unsubstitutedC3 to C30 heteroaryl group, a substituted or unsubstituted C4 to C30heteroarylalkyl group, a substituted or unsubstituted C3 to C30cycloalkyl group, a substituted or unsubstituted C3 to C30heterocycloalkyl group, a C1 to C10 alkoxy group, a hydroxy group, —NH₂,a substituted or unsubstituted C1 to C30 amine group (—NRR′, wherein Rand R′ are the same or different, and are independently hydrogen or a C1to C30 linear or branched alkyl group, and provided that R and R′ arenot hydrogen simultaneously), an isocyanate group, a halogen, —ROR′(wherein R is a substituted or unsubstituted C1 to C20 alkylene groupand R′ is hydrogen or a C1 to C20 linear or branched alkyl group), anacyl halide group (—RC(═O)X, wherein R is a substituted or unsubstitutedC1 to C20 alkylene group and X is a halogen), —C(═O)OR′ (wherein R′ ishydrogen or a C1 to C20 linear or branched alkyl group), —CN, —C(═O)NRR′(wherein R and R′ are the same or different, and are independentlyhydrogen or a C1 to C20 linear or branched alkyl group), —C(═O)ONRR′(wherein R and R′ are the same or different, and are independentlyhydrogen or a C1 to C20 linear or branched alkyl group) or a combinationthereof,

L₁ is a carbon atom, a substituted or unsubstituted C1 to C30 alkylenegroup, a substituted or unsubstituted C2 to C30 alkenylene group, asubstituted or unsubstituted C3 to C30 cycloalkylene group, asubstituted or unsubstituted C6 to C30 arylene group, a substituted orunsubstituted C3 to C30 heteroarylene group, a substituted orunsubstituted C3 to C30 heterocycloalkylene group, or a substituted orunsubstituted C2 to C30 alkylene group or a substituted or unsubstitutedC3 to C30 alkenylene group, having at least one methylene (—CH₂—)replaced by sulfonyl (—S(═O)₂—), carbonyl (—C(═O)—), ether (—O—),sulfide (—S—), sulfoxide (—S(═O)—), ester (—C(═O)O—), amide (—C(═O)NR—)(wherein R is hydrogen or a C1 to C10 alkyl group), or a combinationthereof,

Y₁ is a single bond, a substituted or unsubstituted C1 to C30 alkylenegroup, a substituted or unsubstituted C2 to C30 alkenylene group, or aC1 to C30 alkylene group or a C2 to C30 alkenylene group wherein atleast one methylene (—CH₂—) is replaced by sulfonyl (—S(═O)₂—), carbonyl(—C(═O)—), ether (—O—), sulfide (—S—), sulfoxide (—S(═O)—), ester(—C(═O)O—), amide (—C(═O)NR—) (wherein R is hydrogen or a C1 to C10linear or branched alkyl group), imine (—NR—) (wherein R is hydrogen ora C1 to C10 linear or branched alkyl group), or a combination thereof,

m is an integer of 1 or more,

k1 is 0 or an integer of 1 or more, k2 is an integer of 1 or more, and

a sum of m and k2 is an integer of 3 or more,

provided that m does not exceed the valence of Y₁ when Y₁ is not asingle bond, and

provided that a sum of k1 and k2 does not exceed the valence of L₁.

The thiol compound may include ethoxylated pentaerythritoltetra(3-mercaptopropionate), trimethylolpropanetri(3-mercaptopropionate), trimethylolpropane-tri(2-mercaptoacetate),glycol di-3-mercaptopropionate, polypropylene glycoldi(3-mercaptopropionate), ethoxylated trimethylolpropanetri(3-mercaptopropionate), glycol dimercaptoacetate, ethoxylated glycoldimercaptoacetate, 1,4-bis(3-mercaptobutyryloxy)butane,tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate,1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione,pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritoltetrakis(2-mercaptoacetate), 1,6-hexanedithiol, 1,3-propanedithiol,1,2-ethanedithiol, a polyethylene glycol dithiol including 1 to 10ethylene glycol repeating units, or a combination thereof.

The polymerizable monomer including a carbon-carbon double bond mayinclude a monomer having at least one (meth)acrylate moiety.

The composition may include a plurality of the quantum dots and asolvent. The composition may include, based on the total weight of thecomposition:

about 1 weight percent to about 60 weight percent of the quantum dots;

about 0.5 weight percent to about 60 weight percent of the binderpolymer;

about 0.5 weight percent to about 70 weight percent of the polymerizablemonomer;

optionally, less than or equal to about 50 weight percent of amulti-thiol compound; and

about 0.01 weight percent to about 10 weight percent of thephotoinitiator; and

a balance amount of the solvent.

A viscosity increase of the composition may be less than 10% withrespect to an initial viscosity thereof when the composition is left at4° C. for 144 hours.

In some embodiments, a layered structure includes a substrate (e.g., atransparent substrate); and

a photoluminescent layer disposed on the substrate and including apattern of a quantum dot polymer composite,

wherein the quantum dot polymer composite includes a polymer matrix anda plurality of quantum dots dispersed in the polymer matrix,

the plurality of quantum dots includes the aforementioned quantum dot,

the pattern of the quantum dot polymer composite includes at least onerepeating section selected from a first section emitting a first light,a second section emitting a second light, and a combination thereof.

The polymer matrix may include a crosslinked polymer and a polymerincluding a carboxylic acid group.

The crosslinked polymer may include a thiol-ene polymer, a crosslinkedpoly(meth)acrylate, or a combination thereof.

In embodiments, a method of producing the aforementioned layeredstructure includes:

forming a film of the aforementioned composition on the substrate;

exposing a selected area of the film to light (e.g., having a wavelengthof less than or equal to about 400 nanometers (nm)); and

developing the exposed selected area of the film with an alkalinedeveloper (e.g., an aqueous alkaline solution) to obtain the pattern ofthe quantum dot polymer composite.

In embodiments, a liquid crystal display includes a backlight unitincluding a light source to provide a third light, a lower substratedisposed on (or over) the backlight unit; the aforementioned layeredstructure; and a liquid crystal layer interposed between the lowersubstrate and the layered structure, wherein the layered structure isdisposed such that the photoluminescent layer faces the liquid crystallayer.

In embodiments, a quantum dot polymer composite includes a polymermatrix and a plurality of quantum dots dispersed in the polymer matrix,wherein the plurality of quantum dots includes the aforementionedquantum dot.

The polymer matrix may include a thiol-ene polymer, a (meth)acrylatepolymer, a urethane polymer, an epoxy polymer, a vinyl polymer, asilicone polymer, or a combination thereof.

In embodiments, an electronic device includes the aforementioned quantumdot polymer composite.

The electronic devices may include a light emitting diode (LED), anorganic light emitting diode (OLED), a sensor, an imaging sensor, asolar cell, or a liquid crystal display device.

The quantum dot of the embodiments may have increased light emittingefficiency together with enhanced stability. A composition including thequantum dot of the embodiments may provide improved processability.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram illustrating an exemplary embodiment of amethod of producing a quantum dot polymer composite pattern;

FIG. 2 is a cross-sectional view of an exemplary embodiment of anelectronic device;

FIG. 3 is an exploded view of an exemplary embodiment of an electronicdevice;

FIG. 4 is a graph showing the results of a thermogravimetric analysis ofeach of the quantum dots prepared in Reference Example 1, ComparativeExamples 1 and 2, and Example 1; and

FIG. 5 is a graph showing the results of a Nuclear Magnetic Resonance(NMR) analysis of the quantum dots prepared in Reference Example 1,Comparative Example 1, and Example 1.

DETAILED DESCRIPTION

Advantages and characteristics of this disclosure, and a method forachieving the same, will become evident referring to the followingexample embodiments together with the drawings attached hereto. However,the embodiments should not be construed as being limited to theembodiments set forth herein. If not defined otherwise, all terms(including technical and scientific terms) in the specification may bedefined as commonly understood by one skilled in the art. The termsdefined in a generally-used dictionary may not be interpreted ideally orexaggeratedly unless clearly defined. In addition, unless explicitlydescribed to the contrary, the word “comprise” and variations such as“comprises” or “comprising”, will be understood to imply the inclusionof stated elements but not the exclusion of any other elements.

Further, the singular includes the plural unless mentioned otherwise.

Accordingly, the embodiments are merely described below, by referring tothe figures, to explain aspects of the present description. As usedherein, the term “and/or” includes any and all combinations of one ormore of the associated listed items. The term “or” means “and/or.”Expressions such as “at least one of” when preceding a list of elements,modify the entire list of elements and do not modify the individualelements of the list.

It will be understood that when an element is referred to as being “on”another element, it may be directly on the other element or interveningelements may be present therebetween. In contrast, when an element isreferred to as being “directly on” another element, there are nointervening elements present.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another element, component, region, layer, or section.Thus, a first element, component, region, layer, or section discussedbelow could be termed a second element, component, region, layer, orsection without departing from the teachings of the present embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system).

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

“Combination” as used herein is inclusive of all types of combinations,including blends, alloys, solutions, and the like.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

As used herein, when a definition is not otherwise provided, the term“substituted” refers to a compound or a group or a moiety wherein atleast one of hydrogen atoms thereof is substituted with a substituentincluding a C1 to C30 alkyl group, a C2 to C30 alkenyl group, a C2 toC30 alkynyl group, a C6 to C30 aryl group, a C7 to C30 alkylaryl group,a C1 to C30 alkoxy group, a C1 to C30 heteroalkyl group, a C3 to C30heteroalkylaryl group, a C3 to C30 cycloalkyl group, a C3 to C15cycloalkenyl group, a C6 to C30 cycloalkynyl group, a C2 to C30heterocycloalkyl group, a halogen (—F, —Cl, —Br, or —I), a hydroxy group(—OH), a nitro group (—NO₂), a cyano group (—CN), an amino group (—NRR′,wherein R and R′ are the same or different, and are independentlyhydrogen or a C1 to C6 alkyl group), an azido group (—N₃), an amidinogroup (—C(═NH)NH₂), a hydrazino group (—NHNH₂), a hydrazono group(═N(NH₂), an aldehyde group (—C(═O)H), a carbamoyl group (—C(O)NH₂), athiol group (—SH), an ester group (—C(═O)OR, wherein R is a C1 to C6alkyl group or a C6 to C12 aryl group), a carboxylic acid group (—COOH)or a salt thereof (—C(═O)OM, wherein M is an organic or inorganiccation), a sulfonic acid group (—SO₃H) or a salt thereof (—SO₃M, whereinM is an organic or inorganic cation), a phosphoric acid group (—PO₃H₂)or a salt thereof (—PO₃MH or —PO₃M₂, wherein M is an organic orinorganic cation), or a combination thereof.

As used herein, when a definition is not otherwise provided, the term“monovalent organic functional group” refers to a C1 to C30 alkyl group,a C2 to C30 alkenyl group, a C2 to C30 alkynyl group, a C6 to C30 arylgroup, a C7 to C30 alkylaryl group, a C1 to C30 alkoxy group, a C1 toC30 heteroalkyl group, a C3 to C30 heteroalkylaryl group, a C3 to C30cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C30cycloalkynyl group, or a C2 to C30 heterocycloalkyl group.

As used herein, when a definition is not otherwise provided, the term“hetero” refers to inclusion of at least one (e.g., one to three)heteroatom(s) including N, O, S, Si, or P.

As used herein, when a definition is not otherwise provided, the term“alkylene group” refers to a straight or branched saturated aliphatichydrocarbon group having a valence of at least two, optionallysubstituted with one or more substituents. As used herein, when adefinition is not otherwise provided, the term “arylene group” refers toa functional group having a valence of at least two obtained by removalof at least two hydrogens in an aromatic ring, optionally substitutedwith one or more substituents.

As used herein, when a definition is not otherwise provided, the term“aliphatic organic group” refers to a C1 to C30 linear or branched alkylgroup, C2 to C30 linear or branched alkenyl group, and C2 to C30 linearor branched alkynyl group, the term “aromatic organic group” refers to aC6 to C30 aryl group or a C2 to C30 heteroaryl group, and the term“alicyclic organic group” refers to a C3 to C30 cycloalkyl group, a C3to C30 cycloalkenyl group, and a C3 to C30 cycloalkynyl group.

As used herein, when a definition is not otherwise provided, the term“(meth)acrylate” refers to acrylate and/or methacrylate.

As used herein, when a definition is not otherwise provided, the term“dispersion” refers to a dispersion, wherein a dispersed phase is asolid and a continuous phase includes a liquid. For example, the term“dispersion” may refer to a colloidal dispersion wherein the dissolvedor dispersed phase has a dimension of about 1 nm to about severalmicrometers (μm) (e.g., 1 μm or less, 2 μm or less, or 3 μm or less).

As used herein, when a definition is not otherwise provided, the term“Group” in the term Group III, Group II, and the like refers to a groupof Periodic Table.

As used herein, when a definition is not otherwise provided, “Group III”refers to Group IIIA and Group IIIB, and examples of Group III metal maybe Al, In, Ga, and Tl, but are not limited thereto.

As used herein, when a definition is not otherwise provided, “Group IV”refers to Group IVA and Group IVB, and examples of a Group IV metal maybe Si, Ge, and Sn, but are not limited thereto. As used herein, the term“metal” may include a semi-metal such as Si.

As used herein, when a definition is not otherwise provided, “Group I”refers to Group IA and Group IB, and examples may include Li, Na, K, Rb,and Cs, but are not limited thereto.

As used herein, when a definition is not otherwise provided, “Group V”refers to Group VA, and examples may include N, P, As, Sb, and Bi, butare not limited thereto.

As used herein, when a definition is not otherwise provided, “Group VI”refers to Group VIA, and examples may include S, Se, and Te, but are notlimited thereto.

As used herein, when a definition is not otherwise provided, the term“carboxylic acid group (—COOH) containing polymer” refers to a polymerhaving a repeating unit with a carboxylic acid group.

In an embodiment, a quantum dot includes a semiconductor nanocrystalparticle and a ligand (e.g., bound to a surface thereof). The ligandincludes a first ligand and a second ligand. The first ligand and thesecond ligand include (or are derived from) a polyvalent metal compoundand a thiol compound (e.g., a thiol and a thiolate), respectively. Thepolyvalent metal compound may be present as a moiety (e.g., as a metalcation and its counter ion) derived therefrom. The thiol compound may bebound to a surface of the quantum dot in the form of a moiety derivedfrom the thiol compound. The semiconductor nanocrystal particle mayinclude a core including a first semiconductor nanocrystal and a shellbeing disposed on the core and including a second semiconductornanocrystal. The second semiconductor nanocrystal may include adifferent composition from that of the first semiconductor nanocrystal.

Types of the semiconductor nanocrystal particle are not particularlylimited. The semiconductor nanocrystal particle may be prepared by anyknown method or is a commercially available. For example, thesemiconductor nanocrystal particle (e.g., the first semiconductornanocrystal and/or the second semiconductor nanocrystal) may include aGroup II-VI compound, a Group III-V compound, a Group IV-VI compound, aGroup IV element or compound, a Group compound, a Group I-II-IV-VIcompound, or a combination thereof. In some embodiments, the quantum dotor the semiconductor nanocrystal particle does not include cadmium,lead, mercury, or a combination thereof.

The Group II-VI compound may include:

a binary element compound including CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO,HgS, HgSe, HgTe, MgSe, MgS, or a combination thereof.

a ternary element compound including CdSeS, CdSeTe, CdSTe, ZnSeS,ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS,CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, or a combinationthereof and

a quaternary element compound including ZnSeSTe, HgZnTeS, CdZnSeS,CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe,HgZnSTe, or a combination thereof.

The Group II-VI compound may further include a Group III metal.

The Group III-V compound may include:

a binary element compound including GaN, GaP, GaAs, GaSb, AlN, AlP,AlAs, AlSb, InN, InP, InAs, InSb, or a combination thereof;

a ternary element compound including GaNP, GaNAs, GaNSb, GaPAs, GaPSb,AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb,InZnP, or a combination thereof; and

a quaternary element compound including GaAlNP, GaAlNAs, GaAlNSb,GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP,InAlNAs, InAlNSb, InAlPAs, InAlPSb, or a combination thereof.

The Group III-V compound may further include a Group II metal (e.g.,InZnP).

The Group IV-VI compound may include:

a binary element compound including SnS, SnSe, SnTe, PbS, PbSe, PbTe, ora combination thereof;

a ternary element compound including SnSeS, SnSeTe, SnSTe, PbSeS,PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, or a combination thereof; and

a quaternary element compound including SnPbSSe, SnPbSeTe, SnPbSTe, or acombination thereof.

Examples of the Group compound may include CuInSe₂, CuInS₂, CuInGaSe,and CuInGaS, but are not limited thereto.

Examples of the Group I-II-IV-VI compound may include CuZnSnSe andCuZnSnS, but are not limited thereto.

The Group IV element or compound may include:

a single-elementary substance including Si, Ge, or a combinationthereof; and

a binary element compound including SiC, SiGe, or a combination thereof.

The binary element compound, the ternary element compound, or thequaternary element compound may be respectively included in a uniformconcentration in the particle or partially different concentrations inthe same particle. The semiconductor nanocrystal particle may include acore including a first semiconductor nanocrystal and a shell disposed onat least a portion (or the entire) of a surface of the core andincluding a second semiconductor nanocrystal having a differentcomposition from that of the first semiconductor nanocrystal. At theinterface between the core and the shell, an alloyed interlayer may bepresent or may not be present. The alloyed layer may include ahomogeneous alloy. The alloyed layer may have a concentration gradient.In the gradient alloy, the concentration of an element of the shellradially changes (e.g., decreases or increases toward the core). Inaddition, the shell may include a multi-layered shell having at leasttwo layers wherein adjacent layers have different composition eachother. In the multi-layered shell, each layer may have a singlecomposition. In the multi-layered shell, each layer may have an alloy.In the multi-layered shell, each layer may have a concentration gradientthat changes radially in light of a composition of a semiconductornanocrystal.

In the core-shell semiconductor nanocrystal particle, the materials ofthe shell may have a bandgap energy that is larger than that of thecore, but it is not limited thereto. The materials of the shell may havea bandgap energy that is smaller than that of the core. In the case ofthe multi-layered shell, the energy bandgap of the outermost layermaterial of the shell may be greater than those of the core and theinner layer material of the shell (a layer that is closer to the core).In the case of the multi-layered shell, a semiconductor nanocrystal ofeach layer is selected to have an appropriate bandgap energy, therebyeffectively showing a quantum confinement effect.

The semiconductor nanocrystal particle may have a size (e.g., particlediameter or in the case of a non-spherically shaped particle, a diametercalculated from a two dimensional area of an electron microscopic imageof the particle) of about 1 nm to about 100 nm. In some embodiments, thequantum dot may have a particle diameter of about 1 nm to about 50 nm,for example, from 2 nm (or from 3 nm) to 35 nm. In some embodiments, thequantum dot have a diameter of greater than or equal to about 1 nm,greater than or equal to about 2 nm, greater than or equal to about 3nm, greater than or equal to about 4 nm, or greater than or equal toabout 5 nm. In some embodiments, the quantum dot have a diameter of lessthan or equal to about 50 nm, less than or equal to about 45 nm, lessthan or equal to about 40 nm, less than or equal to about 35 nm, lessthan or equal to about 30 nm, less than or equal to about 25 nm, lessthan or equal to about 20 nm, less than or equal to about 19 nm, lessthan or equal to about 18 nm, less than or equal to about 17 nm, lessthan or equal to about 16 nm, or less than or equal to about 15 nm.

The semiconductor nanocrystal particle may have a generally-used shapein the art, and is not particularly limited. For example, the quantumdot may include spherical, pyramidal, multi-armed, or cubicnanoparticles, nanotubes, nanowires, nanofibers, nanoplate particles, acombination thereof, or the like.

The semiconductor nanocrystal particle may be commercially available ormay be synthesized in any method. For example, several nano-sizedquantum dots may be synthesized by a wet chemical process. In the wetchemical process, precursors react in an organic solvent to grownanocrystal particles, and the organic solvent or a ligand compound maycoordinate (or be bound) to the surface of the semiconductornanocrystal, thereby controlling the growth of the nanocrystal. Examplesof the organic solvent and ligand compound are known.

The quantum dot as prepared may be recovered by pouring an excess amountof a non-solvent to a reaction solution including the quantum dot andcentrifuging the resulting mixture. Examples of the non-solvent includeacetone, ethanol, methanol, and the like, but are not limited thereto.

The quantum dot prepared by the wet chemical method may have an organicligand bonded to a surface thereof. In an embodiment, the organic ligandmay include RCOOH, RNH₂, R₂NH, R₃N, R₃PO, R₃P, ROH, RCOOR′, RPO(OH)₂,R₂POOH (wherein R and R′ are the same or different, and areindependently a C1 to C40 aliphatic hydrocarbon such as C1 to C40 or C5to C24 alkyl group or a C1 to C40 or C5 to C24 alkenyl group or a C6 toC40 aromatic hydrocarbon such as a C5 to C20 aryl group), a polymericorganic ligand, or a combination thereof.

Examples of the organic ligand compound may include:

amine compounds such as methylamine, ethylamine, propylamine,butylamine, pentylamine, hexylamine, octylamine, nonylamine, decylamine,dodecylamine, hexadecylamine, octadecylamine, dimethylamine,diethylamine, dipropylamine, tributylamine, or trioctylamine;

carboxylic acid compounds such as methanoic acid, ethanoic acid,propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoicacid, octanoic acid, dodecanoic acid, hexadecanoic acid, octadecanoicacid, oleic acid, or benzoic acid;

phosphine compounds such as methyl phosphine, ethyl phosphine, propylphosphine, butyl phosphine, pentyl phosphine, octyl phosphine, dioctylphosphine, tributyl phosphine, or trioctyl phosphine;

phosphine oxide compounds such as methyl phosphine oxide, ethylphosphine oxide, propyl phosphine oxide, butyl phosphine oxide, pentylphosphine oxide, tributyl phosphine oxide, octylphosphine oxide, dioctylphosphine oxide, or trioctyl phosphine oxide;

diphenyl phosphine, triphenyl phosphine, or oxide compounds thereof;

a C5 to C20 alkylphosphinic acid such as hexylphosphinic acid,octylphosphinic acid, dodecylphosphinic acid, tetradecylphosphinic acid,hexadecylphosphinic acid, or octadecylphosphinic acid;

and the like, but are not limited thereto.

In some embodiments, the quantum dot may further include at least oneorganic ligand selected from the foregoing.

The light emitting wavelength of the semiconductor nanocrystal particleor the quantum dot is not particularly limited and may be selectedappropriately. The photoluminescent wavelength of the semiconductornanocrystal may be present in a range from a ultraviolet region to anear infrared region. For example, the maximum peak wavelength of thesemiconductor nanocrystal may be present within a range from about 420to about 750 nm, but it is not limited thereto. The semiconductornanocrystal may have a quantum yield (or a quantum efficiency) ofgreater than or equal to about 10%, for example, greater than or equalto about 20%, greater than or equal to about 30%, greater than or equalto about 40%, greater than or equal to about 50%, greater than or equalto about 60%, greater than or equal to about 70%, greater than or equalto about 80%, greater than or equal to about 90%, or even about 100%.

The semiconductor nanocrystal may have a full width half maximum (FWHM)of less than or equal to about 45 nm, for example less than or equal toabout 40 nm, or less than or equal to about 30 nm. While not wishing tobe bound by theory, it is understood that within such ranges, a deviceincluding the nanocrystal may have enhanced color purity or improvedcolor reproducibility.

In order for the quantum dots to be used in a device, they may be mixedwith an organic and/or inorganic matrix. Such mixing and/or fabricationprocess for a device may cause serious deterioration in luminousproperties the quantum dots originally have. For example, a mixing withpolymer and/or a heat/photo treatment for a preparation of a quantum dotpolymer composite may lead to a decrease in a luminous efficiency.Without wishing to be bound by any theory, the mixing and/or thetreatment may cause a loss of ligands present on a surface of thequantum dot and this may cause deterioration of properties.

Quantum dots having unique luminous properties have great potential tobe applied in various devices (e.g., electronic devices). Currently,most of quantum dots having properties that can be used in an electronicdevice are cadmium-based quantum dots. However, cadmium poses seriousthreats to health and environment and is a restricted element. A GroupIII-V based quantum dot is a type of a cadmium free quantum dot.However, the stability (e.g., chemical stability, heat stability, and/orphotostability) of a cadmium free quantum dot (such as a Group III-Vbased quantum dot or a quantum dot having a Group III-V core) may beinferior to the cadmium based quantum dots. Thus, in various processesfor the application into the electronic device, the luminous propertiesof the cadmium free quantum dots may significantly deteriorate.

To prevent or suppress the deterioration of the quantum dot properties,passivation with an organic compound or an organic/inorganic hybridcompound may be used. However, complex processes may be required and/orthe passivation may be considerably hampered by the steric hindrance dueto the moieties of the organic compound and the organic/inorganic hybridcompound and thus cannot provide sufficient protection for the quantumdot surface.

In the case of the quantum dot of the embodiments, a surface exchangereaction may be carried out under a relatively simple and mild conditionfor a relatively short period of time and thereby the first ligandincluding (or being derived therefrom) a polyvalent metal compound andthe second ligand including a monothiol or a cis-type dithiol or athiolate thereof may bound to a surface of the quantum dot. The quantumdot thus prepared may show improved stability (e.g., chemical stabilityand heat stability).

The polyvalent metal compound may include a metal halide and/or anorganic metal compound having a relatively short organic functionalgroup. In some embodiments, the first ligand may include a compoundrepresented by Chemical Formula 1:

MA_(n)  Chemical Formula 1

wherein M is Mg, Ca, Sc, Sn, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Sr,Y, Zr, Nb, Mo, Cd, In, Ba, Au, Hg, or Tl, n is determined depending onthe valency of the M and is an integer of greater than or equal to 2,each A is the same or different, and is independently a C1 to C10organic group, a halogen (such as F, C1, Br or I), or a combinationthereof.

In some embodiments, the first ligand may include a metal that is thesame as the metal present on a surface of the quantum dot. For example,when the outermost layer of the quantum dot includes zinc, the M ofChemical Formula 1 is zinc.

In some embodiments, the A of Chemical Formula 1 may include an organicfunctional group having 2 to 5 carbon atoms or a halogen containinggroup. The A of Chemical Formula 1 may include a C2 to C5 hydrocarbylgroup, RCOO— or ROCO— (wherein R is a C1 to C4 hydrocarbyl group), ahalogen (e.g., fluorine, chlorine, bromine, or iodine), or a combinationthereof.

In some embodiments, the first ligand may include an organic metal salt(e.g., a metal acetate, a metal propionate, a metal butyrate, a metal(meth)acrylate, and the like), a halogenated metal such as a metalchloride, a metal bromide, or a metal iodide, a hydrocarbyl metal suchas an alkylated metal or an arylated metal, a hydrocarbyl metal halide,or a combination thereof. In some embodiments, the first ligand mayinclude a metal chloride such as zinc chloride, indium chloride, cadmiumchloride, aluminum chloride, iron chloride, or a manganese chloride; analkylated metal such as diethyl zinc, dipropyl zinc, dibutyl zinc,triethyl aluminum, tributyl aluminum, or the like; a metal (zinc orindium) carboxylate such as zinc acetate, zinc acrylate, indium acetate,or the like; or a combination thereof. In some embodiments, the firstligand may include a zinc acetate, zinc propionate, zinc butylate, zinc(meth)acrylate, zinc chloride, or a combination thereof.

When being used in a quantum dot passivation process, an organic metalligand having a carbon number greater than or equal to 11 may notprovide sufficient passivation due to the steric hindrance of theorganic moiety. A metal ligand having a relatively short carbon chainmay efficiently passivate a surface of the quantum dot, therebyincreasing the luminous efficiency of the quantum dot. However, thequantum dot passivated by the metal ligand only or the quantum dotpassivated by the metal ligand having a carbon number of greater than orequal to 11 may cause a sharp increase in a composition viscosity or maybring about a gelation of the composition, thus cannot provide aprocessability necessary for the fabrication of the device. The quantumdot of the embodiments includes the thiol-based second ligand that isbound to a surface thereof together with the first ligand, making itpossible to realize enhanced luminous properties and desiredprocessability at the same time.

The second ligand may include a monothiol or monothiolate having onethiol group. The second ligand may include a dithiol or a derivativethereof, wherein two thiol groups are bonded to adjacent two carbonatoms (i.e., disposed in a cis type configuration), respectively. Insome embodiments, the second ligand does not include a carboxylic acidmoiety.

In some embodiments, the second ligand may include a compoundrepresented by Chemical Formula 2:

wherein,

R¹ is hydrogen, a substituted or unsubstituted C1 to C40 (or C1 to C30)linear or branched alkyl group, a C2 to C40 (C1 to C30) linear orbranched alkenyl group, a substituted or unsubstituted C6 to C30 arylgroup, a substituted or unsubstituted C7 to C30 arylalkyl group, asubstituted or unsubstituted C3 to C30 heteroaryl group, a substitutedor unsubstituted C4 to C30 heteroarylalkyl group, a substituted orunsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstitutedC2 to C30 heterocycloalkyl group, a C1 to C10 alkoxy group, a hydroxygroup, —NH₂, a substituted or unsubstituted C1 to C30 amine group(—NRR′, wherein R and R′ are the same or different, and areindependently hydrogen or a C1 to C30 linear or branched alkyl group,and provided that R and R′ are not hydrogen simultaneously), anisocyanate group, a halogen, —ROR′ (wherein R is a substituted orunsubstituted C1 to C20 alkylene group and R′ is hydrogen or a C1 to C20linear or branched alkyl group), an acyl halide group (—RC(═O)X, whereinR is a substituted or unsubstituted C1 to C20 alkylene group and X is ahalogen), —C(═O)OR′ (wherein R′ is hydrogen or a C1 to C20 linear orbranched alkyl group), —CN, —C(═O)NRR′ (wherein R and R′ are the same ordifferent, and are independently hydrogen or a C1 to C20 linear orbranched alkyl group), C(═O)ONRR′ (wherein R and R′ are the same ordifferent, and are independently hydrogen or a C1 to C20 linear orbranched alkyl group) or a combination thereof,

L₁ is a carbon atom, a nitrogen atom, a substituted or unsubstituted C1to C30 alkylene group, a substituted or unsubstituted C2 to C30alkenylene group, a substituted or unsubstituted C3 to C30 cycloalkylenegroup, a substituted or unsubstituted C3 to C30 heterocycloalkylenegroup, a substituted or unsubstituted C6 to C30 arylene group, asubstituted or unsubstituted C3 to C30 heteroarylene group, or asubstituted or unsubstituted C2 to C30 alkylene group or a substitutedor unsubstituted C3 to C30 alkenylene group, having at least onemethylene (—CH₂—) replaced with sulfonyl (—S(═O)₂—), carbonyl (—C(═O)—),ether (—O—), sulfide (—S—), sulfoxide (—S(═O)—), ester (—C(═O)O—), amide(—C(═O)NR—) (wherein R is hydrogen or a C1 to C10 alkyl group), or acombination thereof,

Y₁ is a single bond, —C(═S)—, a substituted or unsubstituted C1 to C30alkylene group, a substituted or unsubstituted C2 to C30 alkenylenegroup, or a substituted or unsubstituted C1 to C30 alkylene group or asubstituted or unsubstituted C2 to C30 alkenylene group wherein at leastone methylene (—CH₂—) is replaced by sulfonyl (—S(═O)₂—), carbonyl(—C(═O)—), ether (—O—), sulfide (—S—), sulfoxide (—S(═O)—), ester(—C(═O)O—), amide (—C(═O)NR—) (wherein R is hydrogen or a C1 to C10linear or branched alkyl group), imine (—NR—) (wherein R is hydrogen ora C1 to C10 linear or branched alkyl group), or a combination thereof,

R is hydrogen or a monovalent metal (e.g., an alkali metal such aslithium, sodium, potassium, or the like);

k1 is 0 or an integer of 1 or more,

k2 is 1 or 2 provided that when k2 is 2, Y₁ is a single bond and the twoSR moieties are bonded to adjacent two carbon atoms in the L₁ moiety,respectively, and

provided that the sum of k1 and k2 does not exceed the valence of Li.

The second ligand may include a substituted or unsubstituted C1 to C40(e.g., C4 to C12) alkyl thiol compound, a substituted or unsubstitutedC2 to C40 mercapto carboxylic acid compound, a substituted orunsubstituted C2 to C40 mercapto carboxylic acid alkyl ester compound, adithiocarbamic acid compound having a C1 to C40 (e.g., C2 to C12) alkylgroup or a metal salt thereof (e.g., dialkyldithiolcarbamate such asdiethyldithiocarbamate), or a combination thereof. The second ligand mayinclude butanethiol, pentanethiol, hexanethiol, heptanethiol,octanethiol, nonanethiol, decanethiol, undecanethiol, dodecanethiol,octadecanethiol, 2-(2-methoxyethoxy)ethanethiol, 3-methoxybutyl3-mercaptopropionate, 3-methoxybutyl mercaptoacetate, thioglycolic acid,3-mercaptopropionic acid, thiopronine, 2-mercaptopropionic acid,2-mercapto propionate, 2-mercaptoethanol, cysteamine, 1-thioglycerol,mercaptosuccinic acid, L-cysteine, dihydrolipoic acid,2-(dimethylamino)ethanethiol, 5-mercaptomethyl tetrazole,2,3-dimercapto-1-propanol glutathione, m(PEG)-SH, dialkyl(e.g.,diethyl)dithiocarbamic acid or a metal salt thereof (e.g.,dialkyldithiocarbamate), or a combination thereof.

The second ligand may include a compound represented by Chemical Formula2-1, Chemical Formula 2-2, or Chemical Formula 2-3:

R^(a)-L-(CRR)_(n)SM  Chemical Formula 2-1

RRNCSSM  Chemical Formula 2-3

wherein

R^(a) includes a substituted or unsubstituted C1 to C24 alkyl group, asubstituted or unsubstituted C2 to C24 alkenyl group, and a substitutedor unsubstituted C5 to C20 aryl group, R is the same or different, andis each independently hydrogen or a substituted or unsubstituted C1 toC24 alkyl group, n is an integer of 0 to 15, L is a direct bond, asulfonyl (—S(═O)₂—), carbonyl (—C(═O)—), ether group (—O—), sulfidegroup (—S—), sulfoxide group (—S(═O)—), ester group (—C(═O)O—), amidegroup (—C(═O)NR—) (wherein R is hydrogen or a C1 to C10 alkyl group), asubstituted or a unsubstituted C1 to C10 alkylene, a substituted or aunsubstituted C2 to C10 alkenylene, or a combination thereof, and M ishydrogen, lithium, sodium, potassium, or a combination thereof.

In some embodiments, R^(a) of Chemical Formula 2-1 may include a C1 toC24 alkyl or C2 to C24 alkenyl group substituted with an alkoxy group(e.g., methoxy, ethoxy, or propoxy), a hydroxyl group, or a combinationthereof. In some embodiments, L of Chemical Formula 2-1 may be asubstituted or unsubstituted C2 to C10 alkylene or a substituted orunsubstituted C3 to C10 alkenylene wherein at least one methylene groupmay be replaced by a sulfonyl (—S(═O)₂—), carbonyl (—C(═O)—), ethergroup (—O—), sulfide group (—S—), sulfoxide group (—S(═O)—), ester group(—C(═O)O—), amide group (—C(═O)NR—) (wherein R is hydrogen or a C1 toC10 alkyl group), or a combination thereof.

The ratio between the first ligand and the second ligand may becontrolled to provide effective passivation. In some embodiments, perone mole of the first ligand, the amount of the second ligand may begreater than or equal to about 0.1 moles and less than or equal to about10 moles, but it is not limited thereto. In some embodiments, the secondligand may be present in an amount greater than that of the firstligand. In some embodiments, the quantum dot having the first and thesecond ligands may provide a composition having a reduced and suitableviscosity (e.g., when it is mixed with a polymer and/or a monomer). Inaddition, in the case of the composition including the quantum dots ofthe embodiments, an increase in the viscosity over time may besuppressed.

In some embodiments, an amount of the first ligand based on thepolyvalent metal compound may be from about 10 wt % to about 90 wt %,for example, from about 10 wt % to 50 wt % or from about 15 wt % toabout 45 wt %, with respect to a total of the first and the secondligands. An amount of the second ligand based on the thiol compound maybe from about 90 wt % to about 10 wt %, for example, from about 10 wt %to 50 wt % or from about 15 wt % to about 45 wt %, with respect to atotal of the first and the second ligands.

In the case of the quantum dot of some embodiments, the first and thesecond ligands may efficiently (e.g., more densely) passivate more siteson a surface of the quantum dot. Without wishing to be bound by anytheory, each of the first ligand and the second ligand may bind thenon-metal element (e.g., sulfur, selenium, or the like) and the metalelement (e.g., zinc), respectively, and thus more sites present on thesurface of the quantum dot may be passivated thereby. In addition, thefirst ligand and the second ligand may interact with each other, makingit possible to carry out passivation under a minimized steric hindrance.In addition, the surface exchanged quantum dots of the embodiments mayshow improved compatibility with respect to more types of mediums andthus may be dispersed therein while deterioration of the efficiency maybe inhibited, providing improved processability.

Therefore, in some embodiments, the first ligand and the second ligandmay sufficiently passivate the surface of the quantum dot, providingenhanced optical properties by removal of surface defects. In addition,the first ligand and the second ligand may be stably bound to thesurface of the quantum dot and thus the stability of the luminousproperties of the quantum dots (e.g., the chemical stability and thethermal stability) may be improved. Accordingly, it may be possible tosuppress a decrease in the efficiency that may occur otherwise when thequantum dots are mixed with a matrix medium or subjected to the heattreatment during the fabrication process of a device including the same.Due to the passivation achieved by the embodiments, the quantum dot mayhave a 5% weight loss temperature (that is, the temperature at which 5%of the weight of the quantum dot is lost) of less than or equal to about400° C., for example, less than or equal to about 390° C., less than orequal to about 380° C., less than or equal to about 370° C., less thanor equal to about 360° C., less than or equal to about 350° C., lessthan or equal to about 340° C., less than or equal to about 330° C.,less than or equal to about 320° C., less than or equal to about 310°C., less than or equal to about 300° C., less than or equal to about290° C. or less than or equal to about 280° C. as determined by athermogravimetric analysis.

The quantum dot of the embodiments may include a greater or lesseramount of organics as determined by the thermogravimetric analysis ofthe quantum dot than the quantum dot prepared in the conventionalmanners. In general, the quantum dots prepared by a conventional wetchemical process may have organic materials in an amount of 15 wt % to20 wt %. For example, however, as determined by the thermogravimetricanalysis, the quantum dots of the embodiments may include organicmaterials in an amount of greater than or equal to about 25 percent byweight (wt %), for example, greater than or equal to about 26 wt %,greater than or equal to about 27 wt %, greater than or equal to about28 wt %, or greater than or equal to about 29 wt %. The quantum dots ofthe embodiments may include organic materials in an amount of less thanor equal to about 15 percent by weight (wt %), for example, less than orequal to about 14 wt % or less than or equal to about 13 wt %, asdetermined by the thermogravimetric analysis. In some embodiments, thequantum dots of the embodiments may include organic materials in anamount of greater than or equal to about 0.1 wt %, for example, greaterthan or equal to about 1 wt %, greater than or equal to about 2 wt %,greater than or equal to about 3 wt %, greater than or equal to about 4wt %, or greater than or equal to about 5 wt %.

The quantum dots of the embodiments may be prepared by obtaining acolloidal quantum dot with an organic ligand coordinating to a surfacethereof (e.g., prepared by the wet chemical method) and carrying out asurface exchange with a compound for the first ligand and a compound forthe second ligand. In some embodiments, the surface exchange reactionmay be carried out under relatively simple and mild conditions in termsof a temperature and a reaction time.

In some embodiments, the surface exchange may be carried out bycontacting the quantum dot with the compound for the first ligand (e.g.,the polyvalent metal compound represented by Chemical Formula 1) and thecompound for the second ligand (e.g., the thiol compound represented byChemical Formula 2) in an organic solvent under predeterminedconditions.

The organic solvent may include a halogenated (e.g., chlorinated)hydrocarbon (e.g., chloroform, dichloroethane, or the like), asubstituted or unsubstituted C6 to C40 aromatic hydrocarbon such astoluene, xylene, or the like, a substituted or unsubstituted C3 (or C6)to C40 cycloaliphatic hydrocarbon such as cyclohexane, a cyclohexylacetate, or the like, a C1 to C10 alcohol such as ethanol, or acombination thereof.

Details for the quantum dots, the polyvalent metal compound, and thethiol compound are the same as set forth above. The conditions of thesurface exchange are not particularly limited and may be selectedappropriately depending on the types of the quantum dots, the firstligand, and the second ligand. In some embodiments, the temperature ofthe surface exchange may be less than or equal to about 90° C., lessthan or equal to about 80° C., less than or equal to about 70° C., oreven less than or equal to about 65° C. In some embodiments, the surfaceexchange of the quantum dots may be performed at a relatively lowtemperature and thus it may be possible to provide a surface exchangedquantum dot without having an adverse effect on the luminous propertiesof the quantum dots. In some embodiments, the surface exchangetemperature may be greater than or equal to room temperature, forexample, greater than or equal to about 30° C., greater than or equal toabout 40° C., or greater than or equal to about 50° C. For example, thetemperature of the surface exchange may be from about 40° C. to about70° C. The surface exchange may be carried out for greater than or equalto about 10 minutes, for example, greater than or equal to about 20minutes, greater than or equal to about 30 minutes, greater than orequal to about 40 minutes, or greater than or equal to about 50 minutes.

The concentration of the quantum dots in the organic solvent may beselected appropriately and is not particularly limited. For example, theamount of the quantum dots may be greater than or equal to about 0.001grams (g), for example, greater than or equal to about 0.1 g or greaterthan or equal to about 0.5 g per 1 milliliter (mL) of the organicsolvent. The amount of the quantum dot may be less than or equal toabout 3 g, for example, less than or equal to about 2 g or less than orequal to about 1 g per 1 mL of the organic solvent.

With respect to the amount of the quantum dot, the amount of thepolyvalent metal compound may be greater than or equal to about 5 moleq., (i.e., 5 molecules of the compound per one quantum dot), forexample, greater than or equal to about 10 mol eq., greater than orequal to about 15 mol eq., greater than or equal to about 20 mol eq.,greater than or equal to about 30 mol eq., greater than or equal toabout 40 mol eq., greater than or equal to about 50 mol eq., greaterthan or equal to about 60 mol eq., greater than or equal to about 70 moleq., greater than or equal to about 80 mol eq., greater than or equal toabout 90 mol eq., or greater than or equal to about 100 mol eq., but itis not limited thereto. With respect to the amount of the quantum dot,the amount of the polyvalent metal compound may be less than or equal toabout 1500 mol eq., for example, less than or equal to about 1000 moleq., less than or equal to about 900 mol eq., less than or equal toabout 800 mol eq., less than or equal to about 700 mol eq., less than orequal to about 600 mol eq., less than or equal to about 500 mol eq.,less than or equal to about 400 mol eq., less than or equal to about 300mol eq., or less than or equal to about 250 mol eq., but it is notlimited thereto.

With respect to the amount of the quantum dot, the amount of the thiolmay be greater than or equal to about 20 mol eq., for example, greaterthan or equal to about 40 mol eq., greater than or equal to about 50 moleq., greater than or equal to about 60 mol eq., greater than or equal toabout 70 mol eq., greater than or equal to about 80 mol eq., greaterthan or equal to about 90 mol eq., or greater than or equal to about 100mol eq., but it is not limited thereto. With respect to the amount ofthe quantum dot, the amount of the thiol may be less than or equal toabout 6000 mol eq., for example, less than or equal to about 5000 moleq., less than or equal to about 4000 mol eq., less than or equal toabout 3000 mol eq., less than or equal to about 2000 mol eq., less thanor equal to about 1000 mol eq., less than or equal to about 900 mol eq.,less than or equal to about 800 mol eq., less than or equal to about 700mol eq., less than or equal to about 600 mol eq., less than or equal toabout 500 mol eq., or less than or equal to about 400 mol eq., but it isnot limited thereto.

The amount ratio between the polyvalent metal compound and the thiolcompound may be selected appropriately. In some embodiments, for thestable ligand exchange, the polyvalent metal compound may be used in anamount that is smaller than that of the thiol compound. For example, perone mole of the polyvalent metal compound, the used amount of the thiolcompound may be greater than 1 mole, for example, greater than or equalto about 2 moles, greater than or equal to about 3 moles, greater thanor equal to about 4 moles, greater than or equal to about 5 moles,greater than or equal to about 6 moles, greater than or equal to about 7moles, greater than or equal to about 8 moles, greater than or equal toabout 9 moles, or greater than or equal to about 10 moles. In someembodiments, per one mole of the polyvalent metal compound, the usedamount of the thiol compound may be from about 2 moles to about 10moles, but it is not limited thereto. When the surface exchange iscarried out in the presence of the excess amount of the thiol compound,the quantum dot surface exchanged with the first and the second ligandsmay show a reduced viscosity in a composition that will be explainedbelow and the increase in the viscosity of the prepared composition overmay be suppressed. In embodiments, the polyvalent metal compound may beused in an amount that is greater than that of the thiol compound.

The surface exchanged quantum dot may show improved mediumdispersability in comparison with the one that does not undergo thesurface exchange. The non-solvent for the surface exchanged quantum dotsmay be selected considering such changes in the dispersability. In someembodiments, the surface exchanged quantum dots may be recovered using ahydrocarbon solvent such as hexane.

In some embodiments, a quantum dot composition includes a quantum dotincluding the first ligand and the second ligand on a surface thereof(i.e., as surface exchanged with those ligands), a binder polymer, apolymerizable monomer having a carbon-carbon double bond; and aphotoinitiator. The composition may further include an organic solvent.The composition may include a multi-thiol compound having a thiol groupat its end terminals. The binder polymer may include a polymer includinga repeating unit that has a carboxylic acid group.

In the compositions, details of the (surface exchanged) quantum dots arethe same as set forth above. The aforementioned quantum dots may haveimproved chemical stability and thereby the quantum efficiencydeterioration that can occur otherwise may be prevented or suppressed.In the composition, the amount of the quantum dots may be controlledappropriately considering the final use and the other components in thecomposition. In some embodiments, the amount of the quantum dot may begreater than or equal to about 1 percent by weight (wt %), for example,greater than or equal to about 2 wt %, greater than or equal to about 3wt %, greater than or equal to about 4 wt %, greater than or equal toabout 5 wt %, greater than or equal to about 6 wt %, greater than orequal to about 7 wt %, greater than or equal to about 8 wt %, greaterthan or equal to about 9 wt %, greater than or equal to about 10 wt %,greater than or equal to about 11 wt %, greater than or equal to about12 wt %, greater than or equal to about 13 wt %, greater than or equalto about 14 wt %, or greater than or equal to about 15 wt %, based onthe total amount of the composition. The amount of the quantum dot maybe less than or equal to about 60 wt %, for example, less than or equalto about 55 wt %, less than or equal to about 50 wt %, less than orequal to about 45 wt %, less than or equal to about 40 wt %, or lessthan or equal to about 35 wt %, based on the total amount of thecomposition.

In some embodiments, in the composition or in a quantum dot-polymercomposite that will be explained below, the amount of the quantum dotmay be about 1 wt % to 70 wt %, based on a total weight of solidcontents (non-volatile components) of the composition. For example,based on a total weight of solid contents of the composition, the amountof the quantum dot may be greater than or equal to about 1 percent byweight (wt %), for example, greater than or equal to about 2 wt %,greater than or equal to about 3 wt %, greater than or equal to about 4wt %, greater than or equal to about 5 wt %, greater than or equal toabout 6 wt %, greater than or equal to about 7 wt %, greater than orequal to about 8 wt %, greater than or equal to about 9 wt %, greaterthan or equal to about 10 wt %, greater than or equal to about 11 wt %,greater than or equal to about 12 wt %, greater than or equal to about13 wt %, greater than or equal to about 14 wt %, greater than or equalto about 15 wt %, greater than or equal to about 16 wt %, greater thanor equal to about 17 wt %, greater than or equal to about 18 wt %,greater than or equal to about 19 wt %, or greater than or equal toabout 20 wt %. Based on a total weight of solid contents of thecomposition, the amount of the quantum dot may be less than or equal toabout 70 wt %, for example, less than or equal to about 65 wt %, lessthan or equal to about 60 wt %, less than or equal to about 55 wt %, orless than or equal to about 50 wt %.

In the composition of the embodiments, the binder polymer may include acarboxylic acid group. The binder polymer may include:

a copolymer of a monomer combination including a first monomer having acarboxylic acid group and a carbon-carbon double bond, a second monomerhaving a carbon-carbon double bond and a hydrophobic moiety and nothaving a carboxylic acid group, and optionally, a third monomer having acarbon-carbon double bond and a hydrophilic moiety and not having acarboxylic acid group;

a multiple aromatic ring-containing polymer including a carboxylic acidgroup (—COOH) and having a backbone structure in a main chain (e.g., abackbone structure incorporated in the main chain), wherein the backbonestructure includes a quaternary carbon atom, which is a part of a cyclicgroup, and two aromatic rings bound to the quaternary carbon atom;

or a combination thereof.

The copolymer may include a first repeating unit derived from the firstmonomer, a second repeating unit derived from the second monomer, andoptionally, a third repeating unit derived from the third monomer.

The first repeating unit may include a unit represented by ChemicalFormula 3-1, a unit represented by Chemical Formula 3-2, or acombination thereof:

wherein

R¹ is hydrogen, a C1 to C3 alkyl group, or —(CH₂)_(n)—COOH (wherein n is0 to 2),

R² is hydrogen, a C1 to C3 alkyl group, or —COOH,

L is a single bond, a divalent C1 to C15 aliphatic hydrocarbon group, adivalent C6 to C30 aromatic hydrocarbon group, a divalent C3 to C30alicyclic hydrocarbon group, or a divalent C1 to C15 aliphatichydrocarbon group substituted with a C6 to C30 aromatic hydrocarbongroup or a C3 to C30 alicyclic hydrocarbon group, and

* indicates a portion linked to an adjacent atom;

wherein R¹ is hydrogen, a C1 to C3 alkyl group, or —(CH₂)_(m)—COOH(wherein m is 0 to 2),

R² is hydrogen or a C1 to C3 alkyl group,

L is a divalent C1 to C15 alkylene group, a divalent C1 to C15 alkylenegroup wherein at least one methylene group is substituted with —C(═O)—,—O—, or —C(═O)O—, a divalent C6 to C30 aromatic hydrocarbon group, adivalent C3 to C30 alicyclic hydrocarbon group, or a divalent C1 to C15aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group, n is aninteger of 1 to 3, and

* indicates a portion linked to an adjacent atom.

The second repeating unit may include a unit represented by ChemicalFormula 4-1, a unit represented by Chemical Formula 4-2, a unitrepresented by Chemical Formula 4-3, a unit represented by ChemicalFormula 4-4, or a combination thereof:

wherein

R¹ is hydrogen or a C1 to C3 alkyl group,

R² is a C1 to C15 aliphatic hydrocarbon group, a C6 to C30 aromatichydrocarbon group, a C3 to C30 alicyclic hydrocarbon group, or a C1 toC15 aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

R³ is hydrogen or a C1 to C3 alkyl group, and

* indicates a portion linked to an adjacent atom;

wherein

R¹ is hydrogen or a C1 to C3 alkyl group,

L is a divalent C1 to C15 alkylene group, a divalent C1 to C15 alkylenegroup wherein at least one methylene group is substituted with —C(═O)—,—O—, or —C(═O)O—, a divalent C6 to C30 aromatic hydrocarbon group, adivalent C3 to C30 alicyclic hydrocarbon group, or a divalent C1 to C15aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

R² is a C1 to C15 aliphatic hydrocarbon group, a C6 to C30 aromatichydrocarbon group, a C3 to C30 alicyclic hydrocarbon group, or a C1 toC15 aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

R³ is hydrogen or a C1 to C3 alkyl group,

n is an integer of 1 to 3, and

* indicates a portion linked to an adjacent atom;

wherein

each of R¹ and R² is independently hydrogen or a C1 to C3 alkyl group,

Ar is a substituted or unsubstituted C6 to C30 aromatic hydrocarbongroup or a substituted or unsubstituted C3 to C30 alicyclic hydrocarbongroup, and

* indicates a portion linked to an adjacent atom;

wherein

R¹ is hydrogen or a C1 to C3 alkyl group,

R² is a C1 to C15 aliphatic hydrocarbon group, a C6 to C30 aromatichydrocarbon group, a C3 to C30 alicyclic hydrocarbon group, or a C1 toC15 aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

R³ is hydrogen or a C1 to C3 alkyl group, and

* indicates a portion linked to an adjacent atom.

The third repeating unit derived from the third monomer may berepresented by Chemical Formula 5:

wherein

each of R¹ and R² is independently hydrogen or a C1 to C3 alkyl group,

L is a divalent C1 to C15 alkylene group, a divalent C1 to C15 alkylenegroup wherein at least one methylene group is substituted with —C(═O)—,—O—, or —C(═O)O—, a divalent C6 to C30 aromatic hydrocarbon group, adivalent C3 to C30 alicyclic hydrocarbon group, or a divalent C1 to C15aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,

Z is a hydroxyl group (—OH), a mercapto group (—SH), or an amino group(—NHR, wherein R is hydrogen or a C1 to C5 alkyl group) and

* indicates a portion linked to an adjacent atom.

Examples of the first monomer may include, but are not limited to,acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaricacid, 3-butenoic acid, carboxylic acid vinyl ester compounds such asvinyl acetate, and vinyl benzoate. The first monomer may include one ormore compounds.

Examples of the second monomer may include, but are not limited to:

alkenyl aromatic compounds such as styrene, α-methyl styrene, vinyltoluene, or vinyl benzyl methyl ether;

unsaturated carboxylic acid ester compounds such as methyl acrylate,methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate,butyl methacrylate, benzyl acrylate, benzyl methacrylate, cyclohexylacrylate, cyclohexyl methacrylate, phenyl acrylate, or phenylmethacrylate;

unsaturated carboxylic acid amino alkyl ester compounds such as 2-aminoethyl acrylate, 2-amino ethyl methacrylate, 2-dimethyl amino ethylacrylate, or 2-dimethyl amino ethyl methacrylate;

maleimides such as N-phenylmaleimide, N-benzylmaleimide,N-alkylmaleimide;

unsaturated carboxylic acid glycidyl ester compounds such as glycidylacrylate or glycidyl methacrylate;

vinyl cyanide compounds such as acrylonitrile or methacrylonitrile; and

unsaturated amide compounds such as acrylamide or methacrylamide,

but are not limited thereto.

As the second monomer, at least one compound may be used.

If present, examples of the third monomer may include 2-hydroxy ethylacrylate, 2-hydroxy ethyl methacrylate, hydroxy propyl acrylate, hydroxypropyl methacrylate, hydroxy butyl acrylate, and hydroxy butylmethacrylate, but are not limited thereto. The third monomer may includeone or more compounds.

In the binder polymer, an amount of the first repeating unit derivedfrom the first monomer may be greater than or equal to about 10 molepercent (mol %), for example, greater than or equal to about 15 mol %,greater than or equal to about 25 mol %, or greater than or equal toabout 35 mol %. In the binder polymer, an amount of the first repeatingunit may be less than or equal to about 90 mol %, for example, less thanor equal to about 89 mol %, less than or equal to about 88 mol %, lessthan or equal to about 87 mol %, less than or equal to about 86 mol %,less than or equal to about 85 mol %, less than or equal to about 80 mol%, less than or equal to about 70 mol %, less than or equal to about 60mol %, less than or equal to about 50 mol %, less than or equal to about40 mol %, less than or equal to about 35 mol %, or less than or equal toabout 25 mol %.

In the binder polymer, an amount of the second repeating unit derivedfrom the second monomer may be greater than or equal to about 10 mol %,for example, greater than or equal to about 15 mol %, greater than orequal to about 25 mol %, or greater than or equal to about 35 mol %. Inthe binder polymer, an amount of the second repeating unit may be lessthan or equal to about 90 mol %, for example, less than or equal toabout 89 mol %, less than or equal to about 88 mol %, less than or equalto about 87 mol %, less than or equal to about 86 mol %, less than orequal to about 85 mol %, less than or equal to about 80 mol %, less thanor equal to about 70 mol %, less than or equal to about 60 mol %, lessthan or equal to about 50 mol %, less than or equal to about 40 mol %,less than or equal to about 35 mol %, or less than or equal to about 25mol %.

In the binder polymer, an amount of the third repeating unit derivedfrom the third monomer may be greater than or equal to about 1 mol %,for example, greater than or equal to about 5 mol %, greater than orequal to about 10 mol %, or greater than or equal to about 15 mol %. Inthe binder polymer, an amount of the third repeating unit may be lessthan or equal to about 30 mol %, for example, less than or equal toabout 25 mol %, less than or equal to about 20 mol %, less than or equalto about 18 mol %, less than or equal to about 15 mol %, or less than orequal to about 10 mol %.

In an embodiment, the binder polymer may be a copolymer of (meth)acrylicacid (i.e., the first monomer) and at least one second or third monomerincluding arylalkyl(meth)acrylate, hydroxyalkyl (meth)acrylate, orstyrene. For example, the binder polymer may include a methacrylicacid/methyl methacrylate copolymer, a methacrylic acid/benzylmethacrylate copolymer, a methacrylic acid/benzyl methacrylate/styrenecopolymer, a methacrylic acid/benzyl methacrylate/2-hydroxy ethylmethacrylate copolymer, or a methacrylic acid/benzylmethacrylate/styrene/2-hydroxy ethyl methacrylate copolymer.

In an embodiment, the binder polymer may include a multiple aromaticring-containing polymer including a carboxylic acid group (—COOH) and amain chain including a backbone structure incorporated therein, whereinthe backbone structure includes a quaternary carbon atom, which is apart of a cyclic group, and two aromatic rings bound to the quaternarycarbon atom. The carboxylic acid group may be bonded to the main chain.

In the multiple aromatic ring-containing polymer, the backbone structuremay include a unit represented by Chemical Formula A:

wherein

* indicates a portion that is linked to an adjacent atom of the mainchain of the binder,

Z¹ is a linking moiety represented by any one of Chemical Formulae A-1to A-6, and in Chemical Formulae A-1 to A-6, * indicates a portion thatis linked to an adjacent atom in the aromatic ring:

wherein R^(a) is hydrogen, an ethyl group, C₂H₄Cl, C₂H₄OH, CH₂CH═CH₂, ora phenyl group,

The multiple aromatic ring-containing polymer may include a structuralunit represented by Chemical Formula B:

wherein

Z¹ is a linking moiety represented by any one of Chemical Formulae A-1to A-6,

L is a single bond, a C1 to C10 alkylene, a C1 to C10 alkylene having asubstituent including a carbon-carbon double bond, a C1 to C10 oxyalkylene, or a C1 to C10 oxy alkylene having a substituent including acarbon-carbon double bond,

A is —NH—, —O—, or a C1 to C10 alkylene,

each of R¹ and R² is independently hydrogen, a halogen, or a substitutedor unsubstituted C1 to C20 alkyl group,

m1 and m2 are the same or different, and are independently an integerranging from 0 to 4,

Z² is a C6 to C40 aromatic organic group, and

* indicate a portion that is linked to an adjacent atom.

In Chemical Formula B, Z² may be any one of Chemical Formula B-1,Chemical Formula B-2, and Chemical Formula B-3:

wherein * indicates a portion that is linked to an adjacent carbonylcarbon,

wherein * indicates a portion that is linked to an adjacent carbonylcarbon,

wherein * indicates a portion that is linked to an adjacent carbonylcarbon,

L is a single bond, —O—, —S—, —C(═O)—, —CH(OH)—, —S(═O)₂—, —Si(CH₃)₂—,—(CH₂)_(p)— (wherein 1≤p≤10), —(CF₂)_(q)— (wherein 1≤q≤10), —CR₂—(wherein R is independently hydrogen, a C1 to C10 aliphatic hydrocarbongroup, a C6 to C20 aromatic hydrocarbon group, or a C3 to C20 alicyclichydrocarbon group), —C(CF₃)₂—, —C(CF₃)(C₆H₅)—, or —C(═O)NH—.

The multiple aromatic ring-containing polymer may include a structuralunit represented by Chemical Formula C:

wherein

each of R¹ and R² is independently hydrogen or a substituted orunsubstituted (meth)acryloyloxyalkyl group,

each of R³ and R⁴ is independently hydrogen, a halogen, or a substitutedor unsubstituted C1 to C20 alkyl group,

Z¹ is a linking moiety represented by any of Chemical Formulae A-1 toA-6,

Z² is an aromatic organic group such as the moieties set forth above,

m1 and m2 are the same or different, and are independently an integerranging from 0 to 4, and

* indicates a portion that is linked to an adjacent atom.

In some embodiments, the multiple aromatic ring-containing polymer maybe an acid adduct of a bisphenol fluorene epoxy acrylate monomer. Forexample, the bisphenol fluorene epoxy acrylate may be prepared byreacting 4,4-(9-fluorenylidene)-diphenol and epichlorohydrin to obtainan epoxy compound having a fluorene moiety, and the epoxy compound isreacted with an acrylic acid to obtain a fluorenyl epoxy acrylate, whichis then further reacted with biphenyl dianhydride and/or phthalicanhydride. The aforementioned reaction scheme may be summarized asbelow:

The multiple aromatic ring-containing polymer may include a functionalgroup represented by Chemical Formula D at one or both terminal ends:

wherein

* indicates a portion that is linked to an adjacent atom, and

Z³ is a moiety represented by one of Chemical Formulae D-1 to D-7:

wherein each of R^(b) and RC is independently hydrogen, a substituted orunsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1to C20 alkyl group, wherein at least one methylene is replaced with anester group, an ether group, or a combination thereof and

* indicates a portion that is linked to an adjacent atom.

wherein R^(d) is O, S, NH, a substituted or unsubstituted C1 to C20alkylene group, a C1 to C20 alkylamine group, or a C2 to C20alkenylamine group.

The multiple aromatic ring-containing polymer may be synthesized by aknown method or is commercially available (e.g., from Nippon SteelChemical Co., Ltd.).

As non-limiting examples, the multiple aromatic ring-containing polymermay include a structural unit derived from a reaction product of afluorene compound such as 9,9-bis(4-hydroxyphenyl)fluorene,9,9-bis(4-aminophenyl)fluorene, 9,9-bis[4-(glycidyloxy)phenyl]fluorene,9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, 9,9-bis-(3,4-dicarboxyphenyl)fluorene dianhydride, or a combination thereof, with anappropriate compound capable of reacting with the fluorene compound. Theappropriate compound capable of reacting with the fluorene compound mayinclude, but are not limited to, an aromatic dianhydride such aspyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride(BPDA), benzophenone tetracarboxylic dianhydride, and naphthalenetetracarboxylic dianhydride; a C2 to C30 diol compound; epichlorohydrin;or a combination thereof.

The fluorene compound, the dianhydrides, the diol compound, and the likeare commercially available, and the reaction conditions therebetween areknown in the art.

The binder polymer may have an acid value of greater than or equal toabout 50 milligrams of KOH per gram of the polymer (mg KOH/g). Forexample, the binder polymer may have an acid value of greater than orequal to about 60 mg KOH/g, greater than or equal to about 70 mg KOH/g,greater than or equal to about 80 mg KOH/g, greater than or equal toabout 90 mg KOH/g, greater than or equal to about 100 mg KOH/g, greaterthan or equal to about 110 mg KOH/g, greater than or equal to about 120mg KOH/g, greater than or equal to about 125 mg KOH/g, or greater thanor equal to about 130 mg KOH/g. The binder polymer may have an acidvalue of, for example, less than or equal to about 250 mg KOH/g, forexample, less than or equal to about 240 mg KOH/g, less than or equal toabout 230 mg KOH/g, less than or equal to about 220 mg KOH/g, less thanor equal to about 210 mg KOH/g, less than or equal to about 200 mgKOH/g, less than or equal to about 190 mg KOH/g, less than or equal toabout 180 mg KOH/g, less than or equal to about 170 mg KOH/g, or lessthan or equal to about 160 mg KOH/g, but it is not limited thereto.

While not wishing to be bound by theory, it is understood that when thequantum dots are mixed with a solution of a binder having the acid valuewithin the aforementioned range to provide a quantum dot-binderdispersion, the obtained quantum dot-binder dispersion may have theimproved compatibility with the other components for the compositions ofthe embodiments (e.g., photopolymerizable monomer, photoinitiator,solvent, etc.), and thereby the quantum dots may be relatively uniformlydispersed in the final composition (e.g., photoresist composition).Thus, the composition of the embodiments may include a quantum dotbinder dispersion including the binder polymer and the quantum dotsdispersed therein.

The binder polymer (e.g., containing the carboxylic acid group) may havea molecular weight of greater than or equal to about 1,000 grams permole (g/mol), for example, greater than or equal to about 2,000 g/mol,greater than or equal to about 3,000 g/mol, or greater than or equal toabout 5,000 g/mol. The binder polymer may have a molecular weight ofless than or equal to about 100,000 g/mol, for example, less than orequal to about 90,000 g/mol, less than or equal to about 80,000 g/mol,less than or equal to about 70,000 g/mol, less than or equal to about60,000 g/mol, less than or equal to about 50,000 g/mol, less than orequal to about 40,000 g/mol, less than or equal to about 30,000 g/mol,less than or equal to about 20,000 g/mol, or less than or equal to about10,000 g/mol.

In the composition, an amount of the binder polymer may be greater thanor equal to about 0.5 wt %, for example, greater than or equal to about1 wt %, greater than or equal to about 5 wt %, greater than or equal toabout 10 wt %, greater than or equal to about 15 wt %, or greater thanor equal to about 20 wt %, based on the total weight of the composition.An amount of the binder polymer may be less than or equal to about 60 wt%, for example, less than or equal to about 59 wt %, less than or equalto about 58 wt %, less than or equal to about 57 wt %, less than orequal to about 56 wt %, less than or equal to about 55 wt %, less thanor equal to about 54 wt %, less than or equal to about 53 wt %, lessthan or equal to about 52 wt %, less than or equal to about 51 wt %,less than or equal to about 50 wt %, less than or equal to about 49 wt%, less than or equal to about 48 wt %, less than or equal to about 47wt %, less than or equal to about 46 wt %, less than or equal to about45 wt %, less than or equal to about 44 wt %, less than or equal toabout 43 wt %, less than or equal to about 42 wt %, less than or equalto about 41 wt %, less than or equal to about 40 wt %, less than orequal to about 39 wt %, less than or equal to about 38 wt %, less thanor equal to about 37 wt %, less than or equal to about 36 wt %, lessthan or equal to about 35 wt %, less than or equal to about 34 wt %,less than or equal to about 33 wt %, less than or equal to about 32 wt%, less than or equal to about 31 wt %, or less than or equal to about30 wt %, based on the total weight of the composition. In an embodiment,an amount of the binder polymer may be 0.5 to 70 wt %, based on thetotal weight of solids (i.e., non-volatiles) of the composition. Whilenot wishing to be bound by theory, it is understood that within theaforementioned range, dispersibility of the quantum dots may be ensured.

In the composition, the photopolymerizable monomer having acarbon-carbon double bond may include a photopolymerizable(meth)acrylate monomer. The photopolymerizable (meth)acrylate monomermay include, but are not limited to, alkyl (meth)acrylate, ethyleneglycol di(meth)acrylate, triethylene glycol di(meth)acrylate, diethyleneglycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritoldi(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, dipentaerythritol di(meth)acrylate,dipentaerythritol tri(meth)acrylate, dipentaerythritolpenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, bisphenol Aepoxy(meth)acrylate, bisphenol A di(meth)acrylate, trimethylolpropanetri(meth)acrylate, ethylene glycol monomethyl ether (meth)acrylate,novolac epoxy (meth)acrylate, propylene glycol di(meth)acrylate,tris(meth)acryloyloxyethyl phosphate, or a combination thereof.

The photopolymerizable (meth)acrylate monomer may include a main monomerhaving 1 to 6 (meth)acrylate groups. If desired, the photopolymerizable(meth)acrylate monomer may include at least one of a first accessorymonomer having 8 to 20 (meth)acrylate groups, and a second accessorymonomer represented by Chemical Formula E:

R¹O-(L₁)_(m)-L₃-A-L₄-(L₂)_(n)-OR²  Chemical Formula E

wherein,

A is a divalent C1 to C40 aliphatic hydrocarbon group, a divalent C6 toC40 aromatic hydrocarbon group, a divalent moiety including two or moreC6 to C40 aromatic hydrocarbon groups linked by a substituted orunsubstituted C1 to C10 alkylene, an ether, or a combination thereof, oran ether (—O—),

L₁ and L₂ are the same or different, and are each independently asubstituted or unsubstituted C2 to C5 oxyalkylene,

m and n are an integer of 0 to 20, provided that they are notsimultaneously 0,

L₃ and L₄ are the same or different, and are each independently a singlebond, —O—(CH₂)_(m)—CH(OH)—CH₂—, or —(CH₂)_(m)—CH(OH)—CH₂—, and

R¹ and R² are the same or different, and are each independently CR₂═CR—(wherein, R is hydrogen or a methyl group) or CR₂═CRCO— (wherein, R ishydrogen or a methyl group).

Types of the main monomer are not particularly limited but may include a(C1 to C20 alkyl) (meth)acrylate, ethylene glycol di(meth)acrylate,triethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate,1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate,neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate,pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate,dipentaerythritol penta(meth)acrylate, dipentaerythritolhexa(meth)acrylate, trimethylol propane tri(meth)acrylate, ethyleneglycol monomethyl ether (meth)acrylate, novolac epoxy (meth)acrylate,propylene glycol di(meth)acrylate, tris(meth)acryloyloxyethyl phosphate,or a combination thereof, but it is not limited thereto.

The quantum dot polymer composite including the first accessory monomerand/or the second accessory monomer may show improved developability andimproved linearity during a patterning process even when the compositionincludes a large amount of quantum dots and/or an inorganic lightdiffusing agent.

The first accessory monomer may have at least 8, for example, at least10, or at least 12 carbon-carbon double bonds (e.g., (meth)acrylategroups). The number of carbon-carbon double bonds of the first accessorymonomer may be less than or equal to about 20. Without being bound byany theory, the introduction of the first accessory monomer increasesthe number of cross-linkable functional groups, and these functionalgroups may participate in a cross-linking reaction, thereby thecomposite may have greater density, and thus, the linearity of theresulting pattern may be improved.

The first accessory monomer may include a hyperbranched(meth)acrylate-based monomer. The hyperbranched monomer may have aregularly branched structure such as a dendrimer. In an embodiment, thehyperbranched monomer may have an incompletely branched or irregularstructure. The first accessory monomer may further include at least one(for example, one to four) hydroxy groups, and the density and thedevelopability of the patterned composite may be improved together. Thefirst accessory monomer may be used alone or as a mixture of at leasttwo compounds.

A weight average molecular weight of the first accessory monomer may begreater than or equal to about 300 grams per mole (g/mol), and forexample, less than or equal to about 10,000 g/mol, for example, fromabout 500 g/mol to about 800 g/mol.

The first accessory monomer may be synthesized by a known method or iscommercially available (e.g., from Shin Nakamura Chemical Co., Ltd. orNippon Kayaku Co., Ltd.).

The second accessory monomer may be represented by Chemical Formula E.For example, the second accessory monomer may be represented by one ofChemical Formula E-1 and Chemical Formula E-2:

wherein,

each R is the same or different, and are each independently —COCR═CR₂ (Ris hydrogen or a methyl group),

a is an integer of 1 to 5,

m and n are the same as defined in Chemical Formula E, and

L is the same or different, and is independently a single bond, C1 toC10 alkylene, or an ether (—O—).

In an exemplary embodiment, the second accessory monomer may includebisphenol A di(meth)acrylate, bisphenol A epoxy (meth)acrylate,bisphenol A ethylene glycol di(meth)acrylate, bisphenol A ethoxylatedi(meth)acrylate, poly(ethylene glycol) reacted with bisphenol Aglycidyl ether, or a combination thereof.

A weight average molecular weight of the second accessory monomer may begreater than or equal to about 300 g/mol, for example, from about 300g/mol to about 10,000 g/mol, or from about 700 g/mol to about 1500g/mol.

When the composition includes a mixture of the photopolymerizablemonomers, an amount of the main monomer may be greater than or equal toabout 60 wt %, for example, greater than or equal to about 65 wt %,based on the total weight of the mixture of the photopolymerizablemonomers. An amount of the main monomer may be less than or equal toabout 90 wt %, for example, less than or equal to about 85 wt %, basedon the total weight of the mixture of the photopolymerizable monomers.

In the photopolymerizable monomer composition, the sum of the firstaccessory monomer and the second accessory monomer may be greater thanor equal to about 10 wt %, for example, greater than or equal to about15 wt %, based on the total weight of the mixture of thephotopolymerizable monomers. In the photopolymerizable monomercomposition, the sum of the first accessory monomer and the secondaccessory monomer may be less than or equal to about 40 wt %, forexample, less than or equal to 35 wt %, based on the total weight of themixture of the photopolymerizable monomers.

When being used, the amount ratio between the first accessory monomerand the second accessory monomer (the amount of the first accessorymonomer:the amount of the second accessory monomer) is about 1:0.1 to1:10, for example, 1:0.2 to 1:5, 1:0.25 to 1:4, 1:0.5 to 1:2, 1:0.7 to1:1.3, or 1:0.75 to 1:1.2. In embodiments, the amount of the firstaccessory monomer is the same or greater than that of the secondaccessory monomer, but it is not limited thereto.

The amount of the photopolymerizable monomer may be greater than orequal to about 0.5 wt %, for example, greater than or equal to about 1wt %, greater than or equal to about 2 wt %, greater than or equal toabout 3 wt %, greater than or equal to about 4 wt %, greater than orequal to about 5 wt %, greater than or equal to about 6 wt %, greaterthan or equal to about 7 wt %, greater than or equal to about 8 wt %,greater than or equal to about 9 wt %, or greater than or equal to about10 wt % with respect to a total amount of the composition. Based on atotal amount of the composition, the amount of the photopolymerizablemonomer may be less than or equal to about 70 wt %, for example, lessthan or equal to about 60 wt %, less than or equal to about 59 wt %,less than or equal to about 58 wt %, less than or equal to about 57 wt%, less than or equal to about 56 wt %, less than or equal to about 55wt %, less than or equal to about 54 wt %, less than or equal to about53 wt %, less than or equal to about 52 wt %, less than or equal toabout 51 wt %, less than or equal to about 50 wt %, less than or equalto about 49 wt %, less than or equal to about 48 wt %, less than orequal to about 47 wt %, less than or equal to about 46 wt %, less thanor equal to about 45 wt %, less than or equal to about 44 wt %, lessthan or equal to about 43 wt %, less than or equal to about 42 wt %,less than or equal to about 41 wt %, less than or equal to about 40 wt%, less than or equal to about 39 wt %, less than or equal to about 38wt %, less than or equal to about 37 wt %, less than or equal to about36 wt %, less than or equal to about 35 wt %, less than or equal toabout 34 wt %, less than or equal to about 33 wt %, less than or equalto about 32 wt %, less than or equal to about 31 wt %, less than orequal to about 30 wt %, less than or equal to about 29 wt %, less thanor equal to about 28 wt %, less than or equal to about 25 wt %, lessthan or equal to about 23 wt %, less than or equal to about 20 wt %,less than or equal to about 18 wt %, less than or equal to about 17 wt%, less than or equal to about 16 wt %, or less than or equal to about15 wt %.

The photoinitiator included in the composition is a compound capable ofinitiating a radical polymerization of the photopolymerizable monomer(e.g., acyclic monomer) and/or the thiol compound (that will beexplained below). Types of the photoinitiator are not particularlylimited. For example, the available photopolymerization initiator mayinclude a triazine compound, an acetophenone compound, a benzophenonecompound, a thioxanthone compound, a benzoin compound, an oximecompound, an aminoketone compound, a phosphine or phosphine oxidecompound, a carbazole compound, a diketone compound, a sulfonium boratecompound, a diazo compound, a diimidazole compound, or a combinationthereof, but it is not limited thereto.

In a non-limiting example, the examples of the triazine compound mayinclude 2,4,6-trichloro-s-triazine,2-phenyl-4,6-bis(trichloromethyl)-s-triazine,2-(3′,4′-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine,2-(4′-methoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine,2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine,2-biphenyl-4,6-bis(trichloromethyl)-s-triazine,2,4-bis(trichloromethyl)-6-styryl-s-triazine,2-(naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine,2-(4-methoxynaphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine,2,4-bis(trichloromethyl)-6-(piperonyl)-s-triazine, and2,4-bis(trichloromethyl)-6-(4′-methoxy styryl)-s-triazine, but are notlimited thereto.

Examples of the acetophenone compound may be 2,2′-diethoxyacetophenone,2,2′-dibutoxyacetophenone, 2-hydroxy-2-methylpropiophenone,p-t-butyltrichloroacetophenone, p-t-butyldichloroacetophenone,4-chloroacetophenone, 2,2′-dichloro-4-phenoxyacetophenone,2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropan-1-one,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, and thelike, but are not limited thereto.

Examples of the benzophenone compound may be benzophenone, benzoylbenzoate, methyl benzoyl benzoate, 4-phenylbenzophenone,hydroxybenzophenone, acrylated benzophenone,4,4′-bis(dimethylamino)benzophenone, 4,4′-dichlorobenzophenone,3,3′-dimethyl-2-methoxybenzophenone, and the like, but are not limitedthereto.

Examples of the thioxanthone compound may be thioxanthone,2-methylthioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone,2,4-diisopropylthioxanthone, 2-chlorothioxanthone, and the like, but arenot limited thereto.

Examples of the benzoin compound may include benzoin, benzoin methylether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutylether, benzyl dimethyl ketal, and the like, but are not limited thereto.

Examples of the oxime compound may be2-(O-benzoyloxime)-1-[4-(phenylthio)phenyl]-1,2-octandione,1-(O-acetyloxime)-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone,and the like, but are not limited thereto.

In the composition, an amount of the photoinitiator may be greater thanor equal to about 0.01 wt %, for example, greater than or equal to about0.1 wt %, or greater than or equal to about 1 wt %, based on the totalweight of the composition. The amount of the photoinitiator may be lessthan or equal to about 10 wt %, for example, less than or equal to about5 wt %, based on the total weight of the composition. However, theamount of the photoinitiator is not limited thereto.

In some embodiments, the composition may further include a multi-thiolcompound having at least two thiol groups at its terminal ends. Themulti-thiol compound may include a compound represented by ChemicalFormula 6:

wherein

R¹ includes hydrogen, a substituted or unsubstituted C1 to C30 linear orbranched alkyl group, a substituted or unsubstituted C1 to C30 linear orbranched alkenyl group, a substituted or unsubstituted C6 to C30 arylgroup, a substituted or unsubstituted C7 to C30 arylalkyl group, asubstituted or unsubstituted C3 to C30 heteroaryl group, a substitutedor unsubstituted C4 to C30 heteroarylalkyl group, a substituted orunsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstitutedC2 to C30 heterocycloalkyl group, a C1 to C10 alkoxy group, a hydroxygroup, —NH₂, a substituted or unsubstituted C1 to C30 amine group(—NRR′, wherein R and R′ are the same or different, and areindependently hydrogen or a C1 to C30 linear or branched alkyl group,and provided that R and R′ are not hydrogen simultaneously); anisocyanate group; a halogen; —ROR′ (wherein R is a substituted orunsubstituted C1 to C20 alkylene group and R′ is hydrogen or a C1 to C20linear or branched alkyl group); an acyl halide group (—RC(═O)X, whereinR is a substituted or unsubstituted C1 to C20 alkylene group and X is ahalogen), —C(═O)OR′ (wherein R′ is hydrogen or a C1 to C20 linear orbranched alkyl group), —CN, —C(═O)NRR′ (wherein R and R′ are the same ordifferent, and are independently hydrogen or a C1 to C20 linear orbranched alkyl group), —C(═O)ONRR′ (wherein R and R′ are the same ordifferent, and are independently hydrogen or a C1 to C20 linear orbranched alkyl group), or a combination thereof,

L₁ includes a carbon atom, a substituted or unsubstituted C1 to C30alkylene group, a substituted or unsubstituted C1 to C30 alkenylenegroup, a substituted or unsubstituted C3 to C30 cycloalkylene group, asubstituted or unsubstituted C6 to C30 arylene group, a substituted orunsubstituted C3 to C30 heteroarylene group, a substituted orunsubstituted C3 to C30 heterocycloalkylene group, wherein at least onemethylene (—CH₂—) of the substituted or unsubstituted C1 to C30 alkylenegroup may be replaced by sulfonyl (—S(═O)₂—), carbonyl (—C(═O)—), ether(—O—), sulfide (—S—), sulfoxide (—S(═O)—), ester (—C(═O)O—), amide(—C(═O)NR—) (wherein R is hydrogen or a C1 to C10 alkyl group), or acombination thereof,

Y₁ includes a single bond, a substituted or unsubstituted C1 to C30alkylene group, a substituted or unsubstituted C2 to C30 alkenylenegroup, or a substituted or unsubstituted C1 to C30 alkylene group or asubstituted or unsubstituted C2 to C30 alkenylene group wherein at leastone methylene (—CH₂—) is replaced by sulfonyl (—S(═O)₂—), carbonyl(—C(═O)—), ether (—O—), sulfide (—S—), sulfoxide (—S(═O)—), ester(—C(═O)O—), amide (—C(═O)NR—) (wherein R is hydrogen or a C1 to C10linear or branched alkyl group), imine (—NR—) (wherein R is hydrogen ora C1 to C10 linear or branched alkyl group), or a combination thereof,

m is an integer of 1 or more,

k1 is 0 or an integer of 1 or more,

k2 is an integer of 1 or more, and

the sum of m and k2 is an integer of 3 or more,

provided that m does not exceed the valence of Y₁ when Y₁ is not asingle bond, and

provided that the sum of k1 and k2 does not exceed the valence of Li.

The multi-thiol compound may include a compound of Chemical Formula 6-1:

wherein

L₁′ is carbon, a substituted or unsubstituted C2 to C20 alkylene group,a substituted or unsubstituted C6 to C30 arylene group, a substituted orunsubstituted C3 to C30 heteroarylene group, a substituted orunsubstituted C3 to C30 cycloalkylene group, or a substituted orunsubstituted C3 to C30 heterocycloalkylene group,

Y_(a) to Y_(d) are the same or different, and are independently a singlebond, a substituted or unsubstituted C1 to C30 alkylene group, asubstituted or unsubstituted C2 to C30 alkenylene group, or asubstituted or unsubstituted C1 to C30 alkylene group or a substitutedor unsubstituted C2 to C30 alkenylene group wherein at least onemethylene (—CH₂—) is replaced by sulfonyl (—S(═O)₂—), carbonyl(—C(═O)—), ether (—O—), sulfide (—S—), sulfoxide (—S(═O)—), ester(—C(═O)O—), amide (—C(═O)NR—) (wherein R is hydrogen or a C1 to C10linear or branched alkyl group), imine (—NR—) (wherein R is hydrogen ora C1 to C10 linear or branched alkyl group), or a combination thereof,and

each of R_(a) to R_(d) is independently R¹ of Chemical Formula 6 or SH,provided that at least two of them are SH.

The multi-thiol compound may link the plurality of the quantum dots toeach other as explained above. In addition, the multi-thiol compound mayparticipate in the reaction with the photopolymerizable monomer withouthaving an adverse effect on the dispersibility of the quantum dots toform a polymerization product (i.e., the thiol-ene polymer). Regardingthe thiol-ene polymer, to the disclosure refers to US-2015-0218444-A1,which is incorporated herein by reference in its entirety.

The multi-thiol compound may include a dithiol compound (other than acis-type dithiol), a trithiol compound, a tetrathiol compound, or acombination thereof. For example, the thiol compound may include glycoldi-3-mercaptopropionate, glycol dimercaptoacetate, trimethylolpropanetris(3-mercaptopropionate), pentaerythritoltetrakis(3-mercaptopropionate), pentaerythritoltetrakis(2-mercaptoacetate), 1,6-hexanedithiol, 1,3-propanedithiol,1,2-ethanedithiol, polyethylene glycol dithiol including 1 to 10ethylene glycol repeating units, or a combination thereof.

In the composition, the amount of the multi thiol compound may be lessthan or equal to about 50 wt %, for example, less than or equal to about49 wt %, less than or equal to about 48 wt %, less than or equal toabout 47 wt %, less than or equal to about 46 wt %, less than or equalto about 45 wt %, less than or equal to about 44 wt %, less than orequal to about 43 wt %, less than or equal to about 42 wt %, less thanor equal to about 41 wt %, less than or equal to about 40 wt %, lessthan or equal to about 39 wt %, less than or equal to about 38 wt %,less than or equal to about 37 wt %, less than or equal to about 36 wt%, less than or equal to about 35 wt %, less than or equal to about 34wt %, less than or equal to about 33 wt %, less than or equal to about32 wt %, less than or equal to about 31 wt %, less than or equal toabout 30 wt %, less than or equal to about 29 wt %, less than or equalto about 28 wt %, less than or equal to about 25 wt %, less than orequal to about 23 wt %, less than or equal to about 20 wt %, less thanor equal to about 18 wt %, less than or equal to about 17 wt %, lessthan or equal to about 16 wt %, less than or equal to about 15 wt %,less than or equal to about 14 wt %, less than or equal to about 13 wt%, less than or equal to about 12 wt %, less than or equal to about 11wt %, less than or equal to about 10 wt %, less than or equal to about 9wt %, less than or equal to about 8 wt %, less than or equal to about 7wt %, less than or equal to about 6 wt %, or less than or equal to about5 wt %, less than or equal to about based on the total weight of thecomposition. The amount of the multi-thiol compound may be greater thanor equal to about 0.1 wt %, for example, greater than or equal to about0.5 wt %, greater than or equal to about 1 wt %, greater than or equalto about 2 wt %, greater than or equal to about 3 wt %, or greater thanor equal to about 4 wt % based on the total weight of the composition.

The composition may further include an organic solvent. Types of thesolvent available for the composition of the embodiments are notparticularly limited. Types and the amount of the solvent may bedetermined depending on the types and the amounts of the foregoing maincomponents (i.e., the quantum dots, the COOH group-containing binder,the photopolymerizable monomer combination, the photoinitiator, and ifpresent, the multi thiol compound,) and other additives. The compositionmay include the solvent in such an amount that the remaining amount ofthe composition other than the amounts of the solid (i.e.,non-volatiles) components is the amount of the solvent. The solvent maybe selected appropriately considering its affinity for other components(e.g., the binder, the photopolymerizable monomer, the photoinitiator,and other additives), its affinity for the alkali developing solution,and its boiling point.

Examples of the solvent may be: ethyl 3-ethoxy propionate; an ethyleneglycol such as ethylene glycol, diethylene glycol, or polyethyleneglycol; a glycol ether such as ethylene glycol monomethyl ether,ethylene glycol monoethyl ether, diethylene glycol monomethyl ether,ethylene glycol diethyl ether, and diethylene glycol dimethyl ether;glycol ether acetates such as ethylene glycol monomethyl ether acetate,ethylene glycol monoethyl ether acetate, diethylene glycol monoethylether acetate, and diethylene glycol monobutyl ether acetate; apropylene glycol such as propylene glycol; propylene glycol ethers suchas propylene glycol monomethyl ether, propylene glycol monoethyl ether,propylene glycol monopropyl ether, propylene glycol monobutyl ether,propylene glycol dimethyl ether, dipropylene glycol dimethyl ether,propylene glycol diethyl ether, and dipropylene glycol diethyl ether;propylene glycol ether acetates such as propylene glycol monomethylether acetate and dipropylene glycol monoethyl ether acetate; amidessuch as N-methylpyrrolidone, dimethyl formamide, and dimethyl acetamide;ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone(MIBK), and cyclohexanone; petroleum products such as toluene, xylene,and solvent naphtha; esters such as ethyl acetate, butyl acetate, andethyl lactate; ethers such as diethyl ether, dipropyl ether, and dibutylether; and combinations thereof.

If desired, the composition may further include various additives suchas a light diffusing agent, a leveling agent, or a coupling agent, inaddition to the aforementioned components. The amount of the additive isnot particularly limited, and may be selected within an appropriaterange, wherein the additive does not cause an adverse effect on thepreparation of the composition, the preparation of the quantum dotpolymer composite, and optionally, the patterning of the composite.

The light diffusing agent may increase a refractive index of thecomposition in order to increase a chance of the incident light to meetwith quantum dots. The light diffusing agent may include inorganic oxideparticles such as alumina, silica, zirconia, titanium oxide, or zincoxide particulates, and metal particles such as gold, silver, copper, orplatinum, but is not limited thereto.

The leveling agent may prevent stains or spots and to improveplanarization and leveling characteristics of a film, and examplesthereof may include the following but are not limited thereto. Forexample, a fluorine-containing leveling agent may include commercialproducts, for example BM-1000® and BM-1100® of BM Chemie Inc.; MEGAFACEF 142D®, F 172®, F 173®, and F 183° of Dainippon Ink Kagaku Kogyo Co.,Ltd.; FC-135®, FC-170C®, FC-430®, and FC-431® of Sumitomo 3M Co., Ltd.;SURFLON S-112®, SURFLON S-113®, SURFLON S-131®, SURFLON S-141®, andSURFLON S-145® of Asahi Glass Co., Ltd.; and SH-28PA®, SH-190®, SH-193®,SZ-6032®, SF-8428®, and the like of Toray Silicone Co., Ltd.

The coupling agent may increase adhesion with respect to the substrate,and examples thereof may include a silane coupling agent. Examples ofthe silane coupling agent may be vinyl trimethoxysilane, vinyltris(2-methoxyethoxysilane), 3-glycidoxypropyltrimethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane,3-methacryloxylpropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane,and the like. Types and the amounts of the additives may be adjusted, ifdesired.

If present, the amount of the additives may be greater than or equal toabout 0.1 wt %, for example, greater than or equal to about 0.5 wt %,greater than or equal to about 1 wt %, greater than or equal to about 2wt %, or greater than or equal to about 5 wt %, but it is not limitedthereto. If present, the amount of the additives may be less than orequal to about 20 wt %, for example, less than or equal to about 19 wt%, less than or equal to about 18 wt %, less than or equal to about 17wt %, less than or equal to about 16 wt %, or less than or equal toabout 15 wt %, but it is not limited thereto.

The composition of the embodiments may be prepared by a method thatincludes:

preparing a quantum dot binder dispersion including the plurality of theaforementioned (surface exchanged) quantum dots, the binder polymer(e.g., capable of containing the carboxylic acid group (COOH)), and anorganic solvent; and

mixing the quantum dot binder dispersion with a photoinitiator, thephotopolymerizable monomer (e.g., (meth)acrylate monomer), optionallythe thiol compound, and optionally, at least one of the foregoingadditives.

The quantum dot binder dispersion may be prepared by mixing a solutionof the binder polymer and a quantum dot solution.

The foregoing components may be mixed in any order or simultaneously.

The composition may have a shear viscosity of less than or equal toabout 10 centipoise (cPs), for example, less than 10 cPs or less than orequal to about 9 cPs, less than or equal to about 8 cPs at a temperatureof about 23° C. to 25° C. The composition may have a shear viscosity ofgreater than or equal to about 2 cPs, for example, greater than or equalto about 3 cPs at a temperature of about 23° C. to 25° C. In someembodiments, the shear viscosity of the composition may be in a range of4 to 6 cPs at a temperature of about 23° C. to 25° C. As used herein,the shear viscosity is a viscosity that can be measured by using arotating concentric cylinder viscometer, a rotating cone and plate typeviscometer, or a rotating parallel disc type viscometer.

In the composition, the quantum dot may have improved stability and thusthe composition may provide enhanced processability without occurrenceof gelation after a predetermined period of time. In some embodiments,the composition does not show a substantial change in viscosity when itis left at a temperature of 4° C. for 144 hours (hrs). For example, whenthe composition is left at a temperature of 4° C. for 144 hrs, aviscosity increase of the composition may be less than or equal to about10%, for example, less than about 10%, less than or equal to about 9%,less than or equal to about 8%, less than or equal to about 7%, lessthan or equal to about 6%, less than or equal to about 5%, less than orequal to about 4%, less than or equal to about 3%, less than or equal toabout 2%, or even less than or equal to about 1% with respect to itsinitial viscosity.

The composition may provide a quantum dot polymer composite via apolymerization (e.g., initiated by light). When the polymerizationoccurs in a selected area, a pattern of the quantum dot polymercomposite may be obtained. If desired, the composite thus obtained mayundergo a post heating or a post baking process for example, at atemperature of 150° C. to 230° C. (e.g., 180° C.) for a predeterminedperiod of time (e.g., 10 minutes (min) or longer or 20 min or longer).

Thus, in embodiments, a layered structure includes a transparentsubstrate and a pattern of a quantum dot polymer composite disposed onthe transparent substrate, wherein the quantum dot polymer compositeincludes a polymer matrix; and a plurality of quantum dots and theplurality of quantum dots includes the aforementioned (surfaceexchanged) quantum dot. The pattern of the quantum dot polymer compositeincludes a first section emitting a first light and a second sectionemitting a second light.

The first light and the second light have different maximum peakemission wavelength in a photoluminescent spectrum. In some embodiments,the first light may be a red light having the maximum peak emissionwavelength at a range from 620 nm to 650 nm, and the second light may bea green light having the maximum peak emission wavelength at a rangefrom 500 nm to 550 nm.

The transparent substrate may be a substrate including an insulatingmaterial. The substrate may include glass; various polymers (e.g.,polyester such as polyethylene terephthalate (PET) or polyethylenenaphthalate (PEN)), polycarbonate, polyimide, polyamide-imide,poly(meth)acrylate, a thiol-ene polymer, and poly(meth)acrylic acid;polysiloxane (e.g. PDMS); an inorganic material such as Al₂O₃ or ZnO; ora combination thereof, but is not limited thereto. As used herein, theterm “transparent” refers to the case where light transmittance isgreater than or equal to about 80%, for example, greater than or equalto about 85% or greater than or equal to about 90% for light (e.g.,excitation light) that excites the quantum dots included in thephotoluminescent layer. A thickness of the transparent substrate may beappropriately selected considering a substrate material but is notparticularly limited. The transparent substrate may have flexibility.

Details of the surface exchanged quantum dot are the same as set forth.

The polymer matrix may include a cross-linked polymer; and a binderpolymer (e.g., a linear polymer) having a carboxylic acid-containingrepeating unit. The cross-lined polymer may include a thiol-ene polymer,a crosslinked poly(meth)acrylate, or a combination thereof. In someembodiments, the crosslinked polymer may include a polymerizationproduct of the aforementioned photopolymerizable monomer and optionallythe multi-thiol compound. Details of the binder polymer are the same asset forth above.

In embodiments, a method of producing the aforementioned layeredstructure includes

forming a film of the aforementioned composition on a transparentsubstrate;

exposing a selected area of the film to light (e.g., having a wavelengthof less than or equal to about 400 nm); and

developing the exposed film with an alkaline developer (such as analkali aqueous solution) to obtain a pattern of a quantum dot polymercomposite.

Details of the transparent substrate and the composition are the same asset forth above. A non-limiting method of forming a pattern is explainedreferring to FIG. 1.

The composition is coated on a transparent substrate in an appropriatemanner such as spin coating or slit coating to form a film of apredetermined thickness (e.g., a thickness of less than or equal toabout 30 μm for example less than or equal to about 10 μm, less than orequal to about 8 μm, less than or equal to about 7 μm and of greaterthan about 3 μm, for example, greater than or equal to about 3.5 μm, orgreater than or equal to about 4 μm). The formed film may be pre-baked,if desired. The temperature, the time, and the atmosphere for theprebaking are known and may be selected appropriately.

The formed (and optionally pre-baked) film is exposed to light having apredetermined wavelength under a mask having a predetermined pattern. Awavelength and intensity of the light may be selected considering thetypes and the amounts of the photoinitiator, the types and the amountsof the quantum dots, and the like.

When the exposed film is treated (e.g., immersed or sprayed) with analkaline developer (e.g., alkaline aqueous solution), the non-exposedareas of the film are dissolved to form a desired pattern. The obtainedpattern may be post-baked, if desired, to improve crack resistance andsolvent resistance of the pattern, for example, at a temperature ofabout 150° C. to about 230° C. for a predetermined time (e.g., greaterthan or equal to about 10 min or greater than or equal to about 20 min).

When a quantum dot-polymer composite is to have a plurality of repeatingsections, a plurality of compositions each including the quantum dotswith a desired light emitting property (e.g., a desired photoluminescentpeak wavelength) is prepared for the formation of each of the repeatingsections and the patterning process is repeated as many times asnecessary (e.g., two times or three times) for each composition toprovide a quantum dot-polymer composite having a desirable pattern. Forexample, the quantum dot polymer composite may be processed to have arepeating pattern having at least two different color sections (e.g.,RGB color sections). The pattern of the quantum dot polymer compositemay replace an absorption type color filter and thus may be used as aphotoluminescent color filter in a display device. The display devicemay be a liquid crystal display device and a display including anorganic light emitting diode (OLED) as a light source.

In some embodiments, a liquid crystal display includes a backlight unitincluding a light source to provide a third light, a lower substratedisposed on the backlight unit; the aforementioned layered structure;and a liquid crystal layer interposed between the lower substrate andthe layered structure, wherein the layered structure is disposed for thephotoluminescent layer to face the liquid crystal layer. A polarizerplate may be disposed below the lower substrate.

FIG. 2 is a cross-sectional view schematically illustrating a displaydevice according to a non-limiting embodiment. Referring to FIG. 2, adisplay device of an embodiment may include a liquid crystal panel 200,a polarizer 300 disposed under the liquid crystal panel 200, and abacklight unit (BLU) disposed under the polarizer 300.

The liquid crystal panel 200 includes a lower substrate 210, a layeredstructure, a liquid crystal layer 220 disposed between the lowersubstrate and the layered structure. The layered structure includes atransparent substrate 240 and a photoluminescent layer 230 that includesa pattern of a quantum dot polymer composite.

The lower substrate 210, also referred to as an array substrate, may bea transparent insulation material substrate (e.g., a glass substrate, apolymer substrate including a polyester such as polyethyleneterephthalate (PET) or polyethylene naphthalate (PEN), polycarbonate,and/or a polyacrylate, inorganic material substrate of a polysiloxane,Al₂O₃, or ZnO). A wire plate 211 is disposed on the lower substrate 210.The wire plate 211 may include a plurality of gate wires (not shown) anddata wires (not shown) that define a pixel area, a thin film transistordisposed adjacent to a crossing region of gate wires and data wires, anda pixel electrode for each pixel area, but is not limited thereto.Details of such a wire plate are known and are not particularly limited.

The liquid crystal layer 220 is disposed on the wire plate 211. Theliquid crystal layer 220 may include an alignment layer 221 on and underthe liquid crystal layer 220 to initially align the liquid crystalmaterial included therein. Details (e.g., a liquid crystal material, analignment layer material, a method of forming liquid crystal layer, athickness of liquid crystal layer, or the like) of the liquid crystalmaterial and the alignment layer are known and are not particularlylimited.

A lower polarizer 300 may be provided under the lower substrate.Materials and structures of the polarizer 300 are known and are notparticularly limited. A backlight unit (e.g., emitting blue light) maybe disposed under the polarizer 300. An upper optical element or anupper polarizer 300 may be provided between the liquid crystal layer 220and the transparent substrate 240, but it is not limited thereto. Forexample, the upper polarizer may be disposed between the liquid crystallayer 220 and the photoluminescent layer 230. The polarizer may be anypolarizer that can be used in a liquid crystal display device. Thepolarizer may be TAC (triacetyl cellulose) having a thickness of lessthan or equal to about 200 μm, but is not limited thereto. In anembodiment, the upper optical element may be a coating that controls arefractive index without a polarization function.

The backlight unit includes a light source 110. The light source mayemit blue light or white light. The light source may include a blue LED,a white LED, or a combination thereof, but is not limited thereto.

The backlight unit may include a light guide panel 120. In anembodiment, the backlight unit may be an edge-type lighting. Forexample, the backlight unit may include a reflector (not shown), a lightguide (not shown) provided on the reflector and providing a planar lightsource with the liquid crystal panel 200, and/or at least one opticalsheet (not shown) on the light guide, for example, a diffusion plate, aprism sheet, and the like, but is not limited thereto. The backlightunit may not have a light guide panel. In some embodiments, thebacklight unit may be a direct-type lighting. For example, the backlightunit may have a reflector (not shown), and may have a plurality offluorescent lamps disposed on the upper side of the reflector at regularintervals, or may have an LED operating substrate on which a pluralityof light emitting diodes are disposed, and over them, a diffusion plateand optionally at least one optical sheet may be provided. Details(e.g., each components of light guide and various optical sheets, areflector, and the like) of such a backlight unit are known and are notparticularly limited.

On the bottom surface of the transparent substrate 240, a black matrix241 having an opening and hiding the gate line, the data line, and thethin film transistor of the wire plate on the lower substrate may beprovided. For example, the black matrix 241 may have a lattice shape. Inthe openings of the black matrix 241, provided is a photoluminescentlayer 230 with a pattern of the quantum dot polymer composite includinga first section (R) configured to emit a first light (e.g., red light),a second section (G) configured to emit a second light (e.g., greenlight), and a third section (B) configured to emit/transmit a thirdlight (e.g., blue light). If desired, the photoluminescent layer mayfurther include at least one fourth section. The fourth section mayinclude a quantum dot emitting different colors (e.g., cyan, magenta,and yellow) from the light emitted from the first to third sections.

In the photoluminescent layer 230, the sections constituting a patternmay be repeated corresponding to the pixel areas formed on the lowersubstrate. A transparent common electrode 231 may be provided on thephotoluminescent layer.

The third section (B) configured to emit/transmit blue light may be atransparent color filter that does not change a light emitting spectrumof the light source. In this case, blue light emitted from the backlightunit may pass the polarizer and the liquid crystal layer and then enteras a polarized light and go out as it is. If needed, the third sectionmay include quantum dots emitting blue light.

If needed, the display device may further include a blue light blockinglayer (blue filter). The blue filter may be disposed between a surfaceof the first section (R) and the second section (G) and the transparentsubstrate 300 or over the transparent substrate (not shown). The bluefilter may be in the form of a sheet having an opening in a regioncorresponding to a pixel area (a third section) displaying blue and thusformed in a region corresponding to first and second sections. In anembodiment, the blue filter may be formed by alternately stacking atleast two layers having different refractive indexes and thus maytransmit light in a blue wavelength region but block light in the otherwavelength regions. The blocked blue light may be reflected andrecycled. The blue filter may block light emitted from a blue lightsource from being directly emitted outside.

In embodiments, a quantum dot polymer composite includes a polymermatrix and a plurality of quantum dots dispersed in the polymer matrix.In some embodiments, the quantum dot polymer composite may be preparedfrom the foregoing composition. In embodiments, the quantum dot polymercomposite may include various types of polymer matrix including athiol-ene polymer, a (meth)acrylate polymer, a urethane polymer, anepoxy polymer, a vinyl polymer, a silicone polymer, or a combinationthereof.

The quantum dot polymer composite may have enhanced stability (e.g.,chemical stability and thermal stability) and thus may maintain anincreased level of photoconversion efficiency even when it is heated at180° C. for 30 minutes.

In the quantum dot polymer composite, the amount of the quantum dot isnot particularly limited and may be selected appropriately. For example,the amount of the quantum dot may be greater than or equal to about 1 wt%, for example, for example, 2 wt %, greater than or equal to about 3 wt%, greater than or equal to about 4 wt %, or greater than or equal toabout 5 wt %, based on a total weight of the composite, but it is notlimited thereto. In the quantum dot polymer composite, the amount of thequantum dot may be less than or equal to about 70 wt %, for example,less than or equal to about 65 wt %, less than or equal to about 60 wt%, less than or equal to about 55 wt %, less than or equal to about 50wt %, less than or equal to about 45 wt %, or less than or equal toabout 40 wt %, based on a total weight of the composite, but it is notlimited thereto.

Embodiments provide an electronic device including the foregoing quantumdot polymer composite. The electronic device may include a lightemitting diode (LED), an organic light emitting diode (OLED), a sensor,a solar cell device, an imaging sensor, or a liquid crystal displaydevice, but it is not limited thereto.

In some non-limiting embodiments, a schematic layered structure of aliquid crystal display device including the quantum dot sheet is shownin FIG. 3. A general structure of the liquid crystal display (LCD) areknown in the art and FIG. 3 schematically shows the same.

Referring to FIG. 3, the liquid crystal display may include a reflector,a light guide panel (LGP), a Blue LED, a quantum dot polymer compositesheet (QD Sheet), various optical sheets such as a prism sheet, a doublebrightness enhance film (DBEF), which are layered to form a layeredstructure, and a liquid crystal module (LCM) or liquid crystal panel maybe disposed on the top of the layered structure.

Hereinafter, the embodiments are illustrated in more detail withreference to examples. However, the present disclosure is not limitedthereto.

EXAMPLES Analysis Method [1] Photoluminescence Analysis

A Hitachi F-7000 spectrometer is used to perform a photoluminescencespectrum analysis with irradiation light of 458 nanometers (nm) (532 nmfor red quantum dot (QD)). The photoluminescence spectrum of the quantumdots is obtained.

[2] Quantum Yield

The quantum yield is obtained by dividing the number of the photonsemitted from the sample by the number of the photons absorbed by thesample. The quantum yield is measured by using HAMAMATSU-Quantaurus-QY,C11347 (purchased from Hamamatsu Co., Ltd.) with respect to a quantumdot containing composition or a quantum dot polymer composite.

[3] Light Conversion Efficiency (CE)

(1) The term “light conversion efficiency” refers to a ratio of emittedlight (e.g., front light) with respect to incident light. The lightconversion efficiency of the quantum dot is a ratio of emitted lightamount of the quantum dot with respect to the light amount absorbed bythe same (e.g., as being dispersed in a composition or in the form of apolymer composite) from the excitation light (e.g., blue light). A totalamount of the excitation light (e.g., a total amount of the blue light,B) may be obtained by integrating a photoluminescent spectrum of theexcitation light. A PL spectrum of the quantum dot polymer composite isobtained and from the obtained PL spectrum, an amount of the blue light(B′) and an amount of the light (A) that is emitted from the quantum dotpolymer composite and has a green and/or red wavelength range aremeasured, respectively. Then, the light conversion efficiency iscalculated by the following equation:

A/(B−B′)×100=light conversion rate (%).

The quantum dot polymer composite film is inserted between the lightguide panel and optical films of a 60 inch television (TV) equipped witha blue LED having a peak wavelength of 449 nm. Then, the TV is operatedand the luminous properties are analysed by using a spectro-radiometer(Konica Minolta, CS-2000) placed 30 centimeters in front of the TV toobtain a photoluminescent spectrum of the emitted light.

[4] Relative Quantum Yield (QY)

The relative QY is a ratio (a percentage) of the quantum yield of thegiven quantum dot with respect to the quantum yield of the referencequantum dot.

[5] Viscosity

The viscosity of the composition is measured by using BrookfieldLVDV-II-Rheometer or HAAKE Rheostress 600.

[6] Thermogravimetric Analysis

A thermogravimetric analysis is carried out by using TA Q5000 (Q5000IR)(manufactured from TA instruments Co. Ltd.)

[7] Nuclear Magnetic Resonance (NMR) Analysis

A NMR analysis for the quantum dot is carried out by using a NMRspectrometer (FT-NMR (500 MHz) (ASCEND 500) of Bruker).

Preparation of Cadmium Free Core-Shell Quantum Dots

Red light emitting quantum dots and Green light emitting quantum dotsare prepared in accordance with the following procedure.

Reference Example 1: Production of Red or Green Light EmittingNon-Cadmium Quantum Dots

(1) 0.2 millimoles (mmol) of indium acetate, optionally 0.1 mmol of zincoleate, 0.6 mmol of palmitic acid, and 10 milliliters (mL) of1-octadecene are placed in a flask, subjected to a vacuum state at 120°C. for one hour, and heated to 280° C. after the atmosphere in the flaskis exchanged with N₂. Then, a mixed solution of 0.1 mmol oftris(trimethylsilyl)phosphine (TMS₃P) and 0.5 mL of trioctylphosphine(TOP) is quickly injected, and the reaction proceeds for a predeterminedtime (e.g., for 20 minutes). The reaction mixture then is rapidly cooledand acetone is added thereto to produce nanocrystals, which are thenseparated by centrifugation and dispersed in toluene to obtain the InPor InZnP core nanocrystals.

0.3 mmol (0.056 grams, g) of zinc acetate, 0.6 mmol (0.189 g) of oleicacid, and 10 mL of trioctylamine are placed in a flask, subjected to avacuum state at 120° C. for 10 minutes, and then heated to 220° C. afterthe atmosphere in the flask is exchanged with N₂. Then, a toluenedispersion of the InP core nanocrystals prepared as described above(optical density: 0.15) and 0.6 mmol of S/TOP (i.e., sulfur dissolved ordispersed in the trioctylphosphine) or a mixture of S/TOP and Se/TOP(with a mole ratio of Se:S=1:3) are added to the flask, and then, theresulting mixture is heated to 280° C., while the reaction proceeds for30 minutes. After the reaction, the reaction solution is quickly cooledto room temperature to obtain a reaction mixture including InP/ZnS orInZnP/ZnSeS semiconductor nanocrystals.

(2) An excess amount of ethanol is added to the reaction mixtureincluding the resulting semiconductor nanocrystals, which is thencentrifuged to remove an extra organic material from the reactionmixture of the semiconductor nanocrystals. After centrifugation, thesupernatant is discarded and the precipitate is dried and dispersed inchloroform to obtain a quantum dot solution (hereinafter, QD solution).A UV-vis absorption spectrum and a photoluminescent spectrum of the QDsolution are measured.

The prepared quantum dot including InP/ZnS semiconductor nanocrystal andthe prepared quantum dot including InZnP/ZnSeS semiconductor nanocrystalabsorb light of a wavelength of 350 nm to 500 nm to emit (red) lighthaving a wavelength of about 600 to 650 nm and (green) light having awavelength of about 520 nm to 550 nm, respectively. The quantum yield ofthe prepared quantum dot is greater than or equal to about 50% (e.g.,50% to 100%).

Preparation of Cadmium Based Core-Shell Quantum Dots Reference Example2: Production of Green Light Emitting Quantum Dots

Green light emitting quantum dots having a CdSe/ZnS alloyed core and aCdZnS shell are prepared as below:

(1) 0.4 millimoles (mmol) of CdO, 0.8 mmol of octadecylphosphonic acid,and 16 g of trioctylamine are placed in a flask, subjected to a vacuumstate at 150° C. with stirring, and heated to 300° C. to form a Cd mixedsolution after the atmosphere in the flask is exchanged with N₂. A Sepowder (Alfa, 200 mesh 99.999%) and trioctylphosphine (Aldrich, 90%) asa 2.0 molar (M) solution are reacted to form a Se precursor, 1 mL ofwhich is rapidly injected to the Cd mixed solution at 300° C. and after2 minutes, the resulting solution is cooled to 50 to 60° C.

After being quickly cooled to room temperature, ethanol is added to thereaction solution and centrifuged to obtain a precipitate (CdSe), whichis then dispersed in toluene.

(2) 0.4 mmol of zinc acetate, 0.8 mmol of oleic acid, and 16 g oftrioctylamine are placed in a flask, subjected to a vacuum state at 150°C., and then heated to 300° C. after the atmosphere in the flask isexchanged with N₂. Then, a toluene dispersion of the CdSe nanocrystalsprepared (1 mL) and 2 mL of n-octanethiol solution diluted with apredetermined amount of trioctylamine (TOA) are added to the reactionflask and then a reaction proceeds for 40 minutes. After the completionof the reaction, the reaction solution is quickly cooled to roomtemperature and ethanol is added thereto and the resulting mixture iscentrifuged to recover a precipitate, which is then dispersed in tolueneto provide a CdSe/ZnS core solution.

(3) 0.05 mmol of cadmium acetate, 0.4 mmol of zinc acetate, 1.5 mL ofoleic acid, and 20 mL of trioctylamine are placed in a reaction flask,subjected to a vacuum state at 120° C. with stirring, and heated to 320°C. after the atmosphere in the flask is exchanged with N₂. 0.6 mL of theCdSe/ZnS core solution and 2 mL of S/TOP are quickly injected and thereaction proceeds for 30 minutes. After the completion of the reaction,the reaction solution is quickly cooled to room temperature, ethanol isadded thereto, and the resulting mixture is centrifuged to obtain aprecipitate, which is then dispersed in chloroform to obtain a cadmiumbased quantum dot solution.

Pattern Formation of Quantum Dot Polymer Composite Reference Example 3

[1] Preparation of Quantum Dot-Binder Dispersion

A chloroform dispersion of green light emitting quantum dots (InP/ZnScore/shell) prepared in Reference Example 1 is mixed with a solution ofa binder polymer of a four membered copolymer of methacrylic acid,benzyl methacrylate, hydroxyethyl methacrylate, and styrene, (acidvalue: 130 milligrams (mg) per gram of KOH (mg KOH/g), molecular weight:8,000 g/mol, acrylic acid:benzyl methacrylate:hydroxyethylmethacrylate:styrene (molar ratio)=61.5%:12%:16.3%:10.2%) (solvent:propylene glycol monomethyl ether acetate, PGMEA, a concentration of 30percent by weight, wt %) to form a quantum dot-binder dispersion.

[2] Preparation of the Photosensitive Composition

To the quantum dot-binder dispersion prepared in item [1], ahexaacrylate having the following structure (as a photopolymerizablemonomer), ethylene glycol di-3-mercaptopropionate (hereinafter, 2T, as amulti-thiol compound), an oxime ester compound (as an initiator), TiO₂(as a light diffusing agent), and PGMEA (as a solvent) are added toobtain a composition.

The prepared compositions includes 12 wt % of quantum dots, 28 wt % ofthe binder polymer, 4.5 wt % of the thiol compound, 2 wt % of thephotopolymerizable monomer, and 0.1 wt % of the photoinitiator, 3 wt %of the light diffusing agent, and a balance amount of the solvent, basedon a total weight of the composition.

[3] Formation of Quantum Dot-Polymer Composite

The composition obtained from item [2] is spin-coated on a glasssubstrate at 150 revolutions per minute (rpm) for 5 seconds (s) toprovide a film. The obtained film is pre-baked at 100° C. for 2 minutes(min) (PRB). The pre-baked film is exposed to light (wavelength: 365nanometers (nm), intensity: 60 millijoules, mJ) under a mask having apredetermined pattern (e.g., a square dot or stripe pattern) for 1 s(EXP) and developed with a potassium hydroxide aqueous solution (conc.:0.043%) for 50 seconds to obtain a quantum dot polymer composite.

[4] Post Bake (POB) Treatment

The patterned film prepared in item [3] is heated at 180° C. for 30minutes for a POB treatment.

For each of the composition, the prebaked film, the exposed film, andthe post baked film, a quantum yield is measured. The ratio of thequantum yield with respect to the initial quantum yield is calculatedfor each of the composition, the prebaked film, the exposed film, andthe post baked film, and the results are shown in Table 1.

Reference Example 4

A quantum dot polymer composite and a pattern thereof are prepared inthe same manner set forth in Reference Example 3 except for using achloroform dispersion of the Cd based quantum dot of Reference Example 2(CdSe alloy core/CdZnS shell, green light emitting). The quantum yieldof each of the composition, the prebaked film, the exposed film, and thepost baked film is measured. The ratio of the quantum yield with respectto the initial quantum yield for each of the composition, the prebakedfilm, the exposed film, and the post baked film is calculated and theresults are shown in Table 1.

TABLE 1 PR After After After initial composition PRB EXP POB Ref.Example 3 100% 81.8% 78.7% 76.1% 60.1% Ref. Example 4 100% 100.4% 93.0%90.1% 88.0%

The results of Table 1 confirm that the indium based cadmium freequantum dot of Reference Example 1 suffers a significant decrease in thequantum efficiency during the preparation of the composition and thequantum dot polymer composite in comparison with the cadmium basedquantum dot of Reference Example 2.

Surface Exchange Treatment for the Quantum Dot with the First Ligand andthe Second Ligand

Example 1

To 50 mL of the QD solution of Reference Example 1 (the amount of thequantum dot is about 1 g), 0.563 g of zinc acrylate (ZA) and 1.6875 mLof dodecanethiol (DDT) are added with respect to the amount of thequantum dot to obtain a reaction solution. The obtained reactionsolution is stirred at 60° C. for 1 hr.

After the stirring, a non-solvent is added to the reaction solution toprecipitate quantum dots, which is then centrifuged to provide a quantumdot surface exchanged with the zinc acrylate and the dodecanethiol(hereinafter, ZA-DDT QD). The ZA-DDT QD is re-dispersed in chloroform.

Example 2

The surface exchange treatment is conducted in the same manner asExample 1 except for using 3-methoxybutyl-3-mercaptopropionate (MBMP)instead of dodecanethiol to obtain a quantum dot surface exchanged withthe zinc acrylate and the 3-methoxybutyl-3-mercaptopropionate(hereinafter, ZA-MBMP QD). The ZA-MBMP QD is re-dispersed in chloroform.

Example 3

The surface exchange treatment is conducted in the same manner asExample 1 except for using hexanethiol (HT) instead of dodecanethiol toobtain a quantum dot surface exchanged with the zinc acrylate and thehexanethiol (hereinafter, ZA-HT QD). The ZA-HT QD is re-dispersed inchloroform.

Example 4

The surface exchange treatment is conducted in the same manner asExample 1 except for using octanethiol (OT) instead of dodecanethiol toobtain a quantum dot surface exchanged with the zinc acrylate and theoctanethiol (hereinafter, ZA-OT QD). The ZA-OT QD is re-dispersed inchloroform.

Example 5

CS₂ and dibutylamine are reacted at room temperature (about 25° C.) for10 minutes to obtain dibutyldithiocarbamic acid.

The surface exchange treatment is conducted in the same manner asExample 1 except for using dibutyldithiocarbamic acid (DTC) instead ofdodecanethiol to obtain a quantum dot surface exchanged with the zincacrylate and the dibutyldithiocarbamic acid (hereinafter, ZA-DTC QD).The ZA-DTC QD is re-dispersed in chloroform.

Example 6

To 50 mL of the green light emitting QD solution of Reference Example 1(the amount of the quantum dot is about 1 g), 0.225 g of zinc acrylate(ZA) and 0.27 mL of MBMP are added with respect to the amount of thequantum dot to obtain a reaction solution. The obtained reactionsolution is stirred at 60° C. for 1 hr.

After the stirring, a non-solvent is added to the reaction solution toprecipitate quantum dots, which is then centrifuged to provide a quantumdot surface exchanged with the zinc acrylate and the MBMP (hereinafter,ZA-MBMP 200-800 QD). The ZA-MBMP 200-800 QD is re-dispersed inchloroform.

Example 7

To 50 mL of the green light emitting QD solution of Reference Example 1(the amount of the quantum dot is about 1 g), 0.1125 g of zinc chloride(ZnCl₂) and 0.27 mL of MBMP are added with respect to the amount of thequantum dot to obtain a reaction solution. The obtained reactionsolution is stirred at 60° C. for 1 hr.

After the stirring, a non-solvent is added to the reaction solution toprecipitate quantum dots, which is then centrifuged to provide a quantumdot surface exchanged with the zinc chloride and the MBMP (hereinafter,ZnCl₂— MBMP 150-800 QD). The ZnCl₂— MBMP 150-800 QD is re-dispersed inchloroform.

Comparative Example 1

The surface exchange treatment is conducted in the same manner asExample 1 except for not using the second ligand (i.e., the thiolcompound) to obtain a quantum dot surface exchanged with the zincacrylate (hereinafter, ZA QD). The ZA QD is re-dispersed in chloroform.

Comparative Example 2

The surface exchange treatment is conducted in the same manner asExample 1 except for not using the first ligand (i.e., the zincacrylate) to obtain a quantum dot surface exchanged with thedodecanethiol (hereinafter, DDT QD). The DDT QD is re-dispersed inchloroform.

Comparative Example 3

The surface exchange treatment is conducted in the same manner asExample 1 except for not using the first ligand (i.e., the zincacrylate) and using 3-methoxybutyl 3-mercaptopropionate (MBMP) insteadof the DDT to obtain a quantum dot surface exchanged with the3-methoxybutyl 3-mercaptopropionate (hereinafter, MBMP QD). The MBMP QDis re-dispersed in chloroform.

Comparative Example 4

The surface exchange treatment is conducted in the same manner asExample 1 except for not using the first ligand (i.e., the zincacrylate) and using octanethiol (OT) instead of the DDT to obtain aquantum dot surface exchanged with the octanethiol (hereinafter, OT QD).The OT QD is re-dispersed in chloroform.

Preparation of Photosensitive Composition Including the SurfaceExchanged Quantum Dot Reference Example 5

Using a chloroform dispersion including any of the surface exchangedquantum dots (InP/ZnS core/shell) prepared in Examples 1 to 4 andComparative Examples 1 to 4 and the quantum dot of Reference Example 1,a photosensitive composition is prepared in the following manner and aquantum dot polymer composite is prepared from each of the preparedcompositions.

[1] Preparation of Quantum Dot-Binder Dispersion

A quantum dot binder dispersion is prepared in the same manner as setforth in Reference Example 3 except for using each of the QD solutionincluding any of the surface exchanged quantum dots (InP/ZnS core/shell)prepared in Examples 1 to 4 and Comparative Examples 1 to 4.

[2] Preparation of Composition

To the quantum dot binder dispersion, prepared in item [1], ahexaacrylate having the following structure (as a photopolymerizablemonomer), ethylene glycol di-3-mercaptopropionate (hereinafter, 2T as amulti-thiol compound), an oxime ester compound (as an initiator), TiO₂(as a light diffusing agent), and PGMEA are added to obtain acomposition.

The prepared compositions includes 12 wt % of quantum dots, 28 wt % ofthe binder polymer, 4.5 wt % of 2 T, 2 wt % of the photopolymerizablemonomer, and 0.1 wt % of the photoinitiator, 3 wt % of the lightdiffusing agent, and a balance amount of the solvent, based on a totalweight of the composition.

[3] Formation of Quantum Dot-Polymer Composite

The composition obtained from item [2] is spin-coated on a glasssubstrate at 150 revolutions per minute (rpm) for 5 seconds (s) toprovide a film. The obtained film is pre-baked at 100° C. for 2 minutes(PRB). The pre-baked film is exposed to light (wavelength: 365 nm,intensity: 60 mJ) for 1 second (s) (EXP) to conduct a polymerization,thereby a quantum dot polymer composite is obtained. The obtainedquantum dot polymer composite is post-baked at 180° C. for 30 minutes.

Evaluation of Properties of the Surface Exchanged Quantum Dot and aQuantum Dot Polymer Composite Including the Same Experimental Example 1

[1] Each of the QD solution of Reference Example 1 (Ref. QD), the QDsolution of Example 2 (ZA-MBMP QD), the QD solution of ComparativeExample 1 (ZA QD), and the QD solution of Comparative Example 3 (MBMPQD) is used to prepare a photosensitive composition and a quantum dotpolymer composite film having a predetermined thickness in the samemanner of Reference Example 5.

[2] For each of the composition prepared by using the QD solution ofReference Example 1 (Ref QD composition), the composition prepared byusing the QD solution of Example 2 (ZA-MBMP QD composition), and thecomposition prepared by using the QD solution of Comparative Example 1(ZA QD composition), an initial viscosity is measured and a viscosity ismeasured again after being left at a temperature of 4° C. for 144 hrs inorder to observe a change in the viscosity with respect to the initialvalue. The results are shown in Table 2.

TABLE 2 Initial Viscosity viscosity after 144 hrs Viscosity (cPs) (cPs)increase Ref QD composition 13.3 13.3 0% ZA-MBMP QD 8.8 8.8 0%composition ZA QD composition 9.0 109.4 (after NA one day)

[3] For each of the composite film prepared from the QD solution ofReference Example 1 (Ref QD film), the composite film prepared from theQD solution of Example 2 (ZA-MBMP QD film), and the composite filmprepared from the QD solution of Comparative Example 3 (MBMP QD film), alight conversion efficiency (C.E., %) is measured after the pre-bakeprocess and after the post bake process, respectively. The results areshown in Table 3. In Table 3, the process maintenance ratio is the C.E.after the POB/the C.E. after the PRB.

TABLE 3 CE after CE after Process maintenance the PRB the POB ratio RefQD FILM 100% 79% 79% ZA-MBMP QD 102% 89% 87% FILM MBMP QD FILM 100% 75%75%

The results of Table 2 and Table 3 confirm that the compositionincluding the QD solution of Comparative Example 1 (ZA QD) has anexcessively high viscosity and thus it is practically impossible toapply the same to a patterning process. The composition prepared fromthe QD solution of Example 2 has a proper initial viscosity and thereoccurs substantially no change in its viscosity when being stored at apredetermined temperature. The quantum dot polymer composite preparedfrom the QD solution of Example 2 has an improved light conversionefficiency even after a heat treatment at a high temperature, incomparison with those of the QD solution of Comparative Example 3 andthe QD solution of Reference Example 1.

Experimental Example 2

Composition 1 (including Ref. QD) and Composition 2 (including ZA-MBMPQD) are prepared in the same manner as Reference Example 3 using the QDsolution of Reference Example 1 (Ref. QD) and the QD solution of Example2 (ZA-MBMP QD), respectively. The QD solution of Reference Example 1,Composition 1, and Composition 2 are stored at 25° C. for 24 hours andthe quantum efficiency of the quantum dot is measured. The results areshown in Table 4.

TABLE 4 Relative quantum efficiency after 24 hours with respect to theinitial quantum efficiency the QD solution of Reference about 100%Example 1 Composition 1 87% Composition 2 about 100%

The results of Table 4 confirm that Composition 2 including the quantumdot of Example 2 may have increased room temperature storage stabilitywith respect to Composition 1 including Ref. QD.

Experimental Example 3

For the QD solution of Example 1 (ZA-DDT QD), the QD solution of Example3 (ZA-HT QD), and the QD solution of Example 4 (ZA-OT QD), and the QDsolution of Comparative Example 1 (ZA QD), Relative Photoluminescent QY(%) is measured based on that of the QD solution of Reference Example 1(Ref. QD) and the results are shown in Table 5. The relative PL QY is aratio of the quantum yield with respect to the PL QY of the Ref. QD.

TABLE 5 The QD included in the solution Relative PLQY (%) Ref. QD 100%ZA-DDT QD 133% ZA-HT QD 121% ZA-OT QD 123% ZA QD 103%

The results of Table 5 confirm that the quantum dot of the Examples mayhave improved PLQY with respect to those of the Ref. QD and the QD ofthe Comparative Examples.

Experimental Example 5

A composition is prepared in the same manner as set forth in ReferenceExample 3 by using the QD solution of Reference Example 1 (Ref. QD), theQD solution of Example 1 (ZA-DDT QD), the QD solution of ComparativeExample 1 (ZA QD), the QD solution of Comparative Example 2 (DDT QD),respectively, and the absolute PL QY (%) is measured for each of thecompositions. The results are shown in Table 6.

TABLE 6 The QD included in the composition Absolute PLQY (%) Ref. QD 67%ZA-DDT QD 82% ZA QD 77% DDT QD 76%

The results of Table 6 confirm that the quantum dots of the Examples mayhave improved quantum efficiency in comparison with the quantum dots ofthe Reference Example and the Comparative Examples, indicating theenhanced chemical stability of the quantum dots prepared in theExamples.

Experimental Example 6

A composition and a quantum dot polymer composite are prepared in thesame manner as set forth in Reference Example 3 by using the QD solutionof Reference Example 1 (Ref. Green QD), the QD solution of Example 6(ZA-MBMP 200-800 Green QD), and the QD solution of Example 7 (ZnCl₂-MBMP150-800, Green QD), respectively, and the viscosity and the lightconversion efficiency are measured for each of the compositions and thecomposites after the PRB and the POB, respectively, and thereby theprocess maintenance ratio (i.e., the C.E. after the POB/the C.E. afterthe PRB) is calculated. The results are shown in Table 7.

TABLE 7 ZA-MBMP ZnCl₂-MBMP Ref. 200-800 150-800, Green QD Green QD GreenQD Light conversion 32.8% 37.6% 36.7% Efficiency (CE) after the POBProcess Maintenance  80%  92%  92% ratio viscosity (1 day, cPs) 4.867.45 4.31

The results of Table 4 confirm that the quantum dot having the first andthe second ligand may have improved thermal stability and luminousproperties after the heat treatment at a high temperature.

Experimental Example 7: TGA Analysis and NMR Analysis

[1] A thermogravimetric analysis is made for each of the quantum dot ofReference Example 1 (QD), the quantum dot of Example 1 (ZA-DDT QD), andthe quantum dot of Comparative Examples 1 and 2 (ZA QD, DDT QD). Theresults are shown in FIG. 4. The results of FIG. 4 confirm that in thecase of the quantum dot of Example 1, the 5% weight loss occurs at arelatively low temperature of less than 300° C. (e.g., less than orequal to about 280° C.) in comparison with those of the ComparativeExamples and the Reference Example. These results may suggest that thesurface of the quantum dot of Example 1 is passivated with the ligandsmore densely than those of the Comparative Examples.

[2] A NMR analysis is made for each of the quantum dot of ReferenceExample 1, the quantum dot of Example 1, and the quantum dot ofComparative Example 1. The results are shown in FIG. 5. In FIG. 5, as tothe quantum dot of Example 1 (ZA-DDT QD), broad peaks are observed at1.2 parts per million (ppm) and 1.6 ppm due to the passivation ligand.In addition, broad peaks caused by the thiol passivation are observedbetween 2.6˜3.0 ppm.

While this disclosure has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A composition comprising a quantum dot and apolymerizable monomer comprising a carbon-carbon double bond, whereinthe quantum dot comprises: a semiconductor nanocrystal particle; a firstligand bound to a surface of the semiconductor nanocrystal particle; anda second ligand bound to the surface of the semiconductor nanocrystalparticle, wherein the second ligand comprises a compound represented byChemical Formula 2-1, Chemical Formula 2-2, or Chemical Formula 2-3:R^(a)-L-(CRR)_(n)SM  Chemical Formula 2-1

RRNCSSM  Chemical Formula 2-3 wherein R^(a) includes hydrogen, asubstituted or unsubstituted C1 to C40 alkyl group, a substituted orunsubstituted C2 to C40 alkenyl group, a substituted or unsubstituted C6to C40 aryl group, a C1 to C10 alkoxy group, or —ROR′ (wherein R is asubstituted or unsubstituted C1 to C20 alkylene group and R′ is hydrogenor a C1 to C20 linear or branched alkyl group), R is the same ordifferent, and is each independently hydrogen or a substituted orunsubstituted C1 to C24 alkyl group, n is an integer of 0 to 15, L is adirect bond, a sulfonyl (—S(═O)₂—), carbonyl (—C(═O)—), ether group(—O—), sulfide group (—S—), sulfoxide group (—S(═O)—), ester group(—C(═O)O—), amide group (—C(═O)NR—) (wherein R is hydrogen or a C1 toC10 alkyl group), a substituted or a unsubstituted C1 to C10 alkylene, aC2 to C10 alkenylene, or a combination thereof, and M is hydrogen,lithium, sodium, potassium, or a combination thereof, wherein the firstligand comprises a compound represented by Chemical Formula 1:MA_(n)  Chemical Formula 1 wherein M is Mg, Ca, Zn, Ga, or In, n isdetermined depending on a valency of the M and is an integer of greaterthan or equal to 2, each A is the same or different, and isindependently a C1 to C10 organic group, a halogen, or a combinationthereof, and wherein the first ligand comprises an organic metal salt, ahalogenated metal, a hydrocarbyl metal, a hydrocarbyl metal halide, or acombination thereof.
 2. The composition of claim 1, wherein when thecomposition is left at 4° C. for 144 hours, an increase of a viscosityof the composition is less than about 10% with respect to an initialviscosity of the composition.
 3. The composition of claim 1, wherein thesemiconductor nanocrystal particle comprises a Group II-VI compound, aGroup III-V compound, a Group IV-VI compound, a Group IV element orcompound, a Group compound, a Group I-II-IV-IV compound, or acombination thereof.
 4. The composition of claim 1, wherein thesemiconductor nanocrystal particle comprises a core comprising a firstsemiconductor nanocrystal and a shell disposed on the core, andcomprising a second semiconductor nanocrystal.
 5. The composition ofclaim 1, wherein the A of Chemical Formula 1 comprises a C2 to C5organic functional group.
 6. The composition of claim 1, wherein the Aof Chemical Formula 1 comprises a C2 to C5 hydrocarbyl group, RCOO— orROCO— (wherein R is a C1 to C4 hydrocarbyl group), fluorine, chlorine,bromine, iodine, or a combination thereof.
 7. The composition of claim1, wherein the first ligand comprises a metal that is the same as ametal present on the surface of the quantum dot.
 8. The composition ofclaim 1, wherein the first ligand comprises indium chloride, cadmiumchloride, aluminum chloride, iron chloride, manganese chloride, diethylzinc, dipropyl zinc, triethyl aluminum, tributyl aluminum, a zinccarboxylate, a zinc (meth)acrylate, zinc chloride, indium acetate, or acombination thereof.
 9. The composition of claim 1, wherein the firstligand comprises a zinc acetate, a zinc propionate, a zinc butyrate, azinc (meth)acrylate, a zinc chloride, or a combination thereof.
 10. Thecomposition of claim 1, wherein the second ligand comprises a C1 to C40alkyl thiol compound, a C1 to C40 alkyl thiol compound substituted withany of a hydroxyl group, a carboxylic acid group or a salt thereof, anester group, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a formyl group, or a combination thereof, a C2to C40 mercapto carboxylic acid compound, a C2 to C40 mercaptocarboxylic acid alkyl ester compound, a dithiocarbamic acid ordithiocarbamate compound comprising a C1 to C40 alkyl group, or acombination thereof.
 11. The composition of claim 1, wherein the quantumdot has a 5% weight loss temperature of less than or equal to about 400°C. as determined by a thermogravimetric analysis.
 12. The composition ofclaim 1, wherein the composition further comprises an initiator, anorganic solvent, or a combination thereof.
 13. The composition of claim12, wherein the organic solvent comprises an ester compound, an ethercompound, a petroleum compound, a ketone compound, an amide compound, ora combination thereof.
 14. The composition of claim 1, wherein thecomposition has a viscosity of greater than about 6 cPs.
 15. Thecomposition of claim 1, wherein the composition further comprises atleast one of a first monomer comprising a carboxylic acid group and acarbon-carbon double bond, a second monomer comprising a carbon-carbondouble bond and a hydrophobic moiety and not comprising a carboxylicacid group, and a third monomer comprising a carbon-carbon double bondand a hydrophilic moiety and not comprising a carboxylic acid group. 16.The composition of claim 15, wherein the first monomer, the secondmonomer, and the third monomer are configured to form a first repeatingunit, a second repeating unit, and a third repeating unit in a polymervia polymerization reaction, respectively, and wherein the firstrepeating unit comprises a unit represented by Chemical Formula 3-1, aunit represented by Chemical Formula 3-2, or a combination thereof:

wherein R¹ is hydrogen, a C1 to C3 alkyl group, or —(CH₂)_(n)—COOH(wherein n is 0 to 2), R² is hydrogen, a C1 to C3 alkyl group, or —COOH,L is a single bond, a C1 to C15 aliphatic hydrocarbon group, a C6 to C30aromatic hydrocarbon group, a C3 to C30 alicyclic hydrocarbon group, ora C1 to C15 aliphatic hydrocarbon group substituted with a C6 to C30aromatic hydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,and * indicates a portion linked to an adjacent atom;

wherein R¹ is hydrogen, a C1 to C3 alkyl group, or —(CH₂)_(n)—COOH(wherein n is 0 to 2), R² is hydrogen or a C1 to C3 alkyl group, L is aC1 to C15 alkylene group, a C1 to C15 alkylene group wherein at leastone methylene group is substituted with —C(═O)—, —O—, or —C(═O)O—, a C6to C30 aromatic hydrocarbon group, a C3 to C30 alicyclic hydrocarbongroup, or a C1 to C15 aliphatic hydrocarbon group substituted with a C6to C30 aromatic hydrocarbon group or a C3 to C30 alicyclic hydrocarbongroup, n is an integer of 1 to 3, and * indicates a portion linked to anadjacent atom; the second repeating unit comprises a repeating unitrepresented by Chemical Formula 4-1, a repeating unit represented byChemical Formula 4-2, a repeating unit represented by Chemical Formula4-3, a repeating unit represented by Chemical Formula 4-4, or acombination thereof:

wherein R¹ is hydrogen or a C1 to C3 alkyl group, R² is a C1 to C15aliphatic hydrocarbon group, a C6 to C30 aromatic hydrocarbon group, aC3 to C30 alicyclic hydrocarbon group, or a C1 to C15 aliphatichydrocarbon group substituted with a C6 to C30 aromatic hydrocarbongroup or a C3 to C30 alicyclic hydrocarbon group, R³ is hydrogen or a C1to C3 alkyl group, * indicates a portion linked to an adjacent atom;

wherein R¹ is hydrogen or a C1 to C3 alkyl group, L is a C1 to C15alkylene group, a C1 to C15 alkylene group wherein at least onemethylene group is substituted with —C(═O)—, —O—, or —C(═O)O—, a C6 toC30 aromatic hydrocarbon group, a C3 to C30 alicyclic hydrocarbon group,or a C1 to C15 aliphatic hydrocarbon group substituted with a C6 to C30aromatic hydrocarbon group or a C3 to C30 alicyclic hydrocarbon group,R² is a C1 to C15 aliphatic hydrocarbon group, a C6 to C30 aromatichydrocarbon group, a C3 to C30 alicyclic hydrocarbon group, or a C1 toC15 aliphatic hydrocarbon group substituted with a C6 to C30 aromatichydrocarbon group or a C3 to C30 alicyclic hydrocarbon group, R³ ishydrogen or a C1 to C3 alkyl group, n is an integer of 1 to 3, and *indicates a portion linked to an adjacent atom;

wherein each of R¹ and R² is independently hydrogen or a C1 to C3 alkylgroup, Ar is a substituted or unsubstituted C6 to C30 aromatichydrocarbon group or a substituted or unsubstituted C3 to C30 alicyclichydrocarbon group, and * indicates a portion linked to an adjacent atom;

wherein R¹ is hydrogen or a C1 to C3 alkyl group, R² is a C1 to C15aliphatic hydrocarbon group, a C6 to C30 aromatic hydrocarbon group, aC3 to C30 alicyclic hydrocarbon group, or a C1 to C15 aliphatichydrocarbon group substituted with a C6 to C30 aromatic hydrocarbongroup or a C3 to C30 alicyclic hydrocarbon group, R³ is hydrogen or a C1to C3 alkyl group, and * indicates a portion linked to an adjacent atom;wherein the third repeating unit is represented by Chemical Formula 5:

wherein each of R¹ and R² is independently hydrogen or a C1 to C3 alkylgroup, L is a C1 to C15 alkylene group, a C1 to C15 alkylene groupwherein at least one methylene group is substituted with —C(═O)—, —O—,or —C(═O)O—, a C6 to C30 aromatic hydrocarbon group, a C3 to C30alicyclic hydrocarbon group, or a C1 to C15 aliphatic hydrocarbon groupsubstituted with a C6 to C30 aromatic hydrocarbon group or a C3 to C30alicyclic hydrocarbon group, Z is a hydroxyl group (—OH), a mercaptogroup (—SH), or an amino group (—NHR, wherein R is hydrogen or a C1 toC5 alkyl group), and *indicates a portion linked to an adjacent atom.17. The composition of claim 1, wherein the composition furthercomprises a thiol compound represented by Chemical Formula 6:

wherein R¹ comprises hydrogen, a substituted or unsubstituted C1 to C30linear or branched alkyl group, a substituted or unsubstituted C1 to C30linear or branched alkenyl group, a substituted or unsubstituted C6 toC30 aryl group, a substituted or unsubstituted C7 to C30 arylalkylgroup, a substituted or unsubstituted C3 to C30 heteroaryl group, asubstituted or unsubstituted C4 to C30 heteroarylalkyl group, asubstituted or unsubstituted C3 to C30 cycloalkyl group, a substitutedor unsubstituted C2 to C30 heterocycloalkyl group, a C1 to C10 alkoxygroup, a hydroxy group, —NH₂, a substituted or unsubstituted C1 to C30amine group (—NRR′, wherein R and R′ are the same or different, and areindependently hydrogen or a C1 to C30 linear or branched alkyl group,and provided that R and R′ are not hydrogen simultaneously); anisocyanate group; a halogen; —ROR′ (wherein R is a substituted orunsubstituted C1 to C20 alkylene group and R′ is hydrogen or a C1 to C20linear or branched alkyl group); an acyl halide group (—RC(═O)X, whereinR is a substituted or unsubstituted C1 to C20 alkylene group and X is ahalogen), —C(═O)OR′ (wherein R′ is hydrogen or a C1 to C20 linear orbranched alkyl group), —CN, —C(═O)NRR′ (wherein R and R′ are the same ordifferent, and are independently hydrogen or a C1 to C20 linear orbranched alkyl group), —C(═O)ONRR′ (wherein R and R′ are the same ordifferent, and are independently hydrogen or a C1 to C20 linear orbranched alkyl group), or a combination thereof, L₁ comprises a carbonatom, a substituted or unsubstituted C1 to C30 alkylene group, asubstituted or unsubstituted C3 to C30 cycloalkylene group, asubstituted or unsubstituted C6 to C30 arylene group, a substituted orunsubstituted C3 to C30 heteroarylene group, a substituted orunsubstituted C3 to C30 heterocycloalkylene group, or a substituted orunsubstituted C1 to C30 alkylene group comprising at least one methylene(—CH₂—) replaced with sulfonyl (—S(═O)₂—), carbonyl (—C(═O)—), ether(—O—), sulfide (—S—), sulfoxide (—S(═O)—), ester (—C(═O)O—), amide(—C(═O)NR—) (wherein R is hydrogen or a C1 to C10 alkyl group), or acombination thereof, Y₁ comprises a single bond, a substituted orunsubstituted C1 to C30 alkylene group, a substituted or unsubstitutedC2 to C30 alkenylene group, or a substituted or unsubstituted C1 to C30alkylene group or a substituted or unsubstituted C2 to C30 alkenylenegroup wherein at least one methylene (—CH₂—) is replaced by sulfonyl(—S(═O)₂—), carbonyl (—C(═O)—), ether (—O—), sulfide (—S—), sulfoxide(—S(═O)—), ester (—C(═O)O—), amide (—C(═O)NR—) (wherein R is hydrogen ora C1 to C10 linear or branched alkyl group), imine (—NR—) (wherein R ishydrogen or a C1 to C10 linear or branched alkyl group), or acombination thereof, m is an integer of 1 or more, k1 is 0 or an integerof 1 or more, k2 is an integer of 1 or more, and a sum of m and k2 is aninteger of 3 or more, provided that m does not exceed the valence of Y₁when Y₁ is not a single bond, and provided that a sum of k1 and k2 doesnot exceed the valence of Li.
 18. The composition of claim 1, whereinthe polymerizable monomer comprising a carbon-carbon double bondcomprises a monomer comprising at least one (meth)acrylate moiety.
 19. Aquantum dot-polymer composite comprising: a polymer matrix; and aplurality of quantum dots dispersed in the polymer matrix; wherein theplurality of quantum dots comprises a quantum dot comprising asemiconductor nanocrystal particle; a first ligand bound to a surface ofthe semiconductor nanocrystal particle; and a second ligand bound to thesurface of the semiconductor nanocrystal particle, wherein the secondligand comprises a compound represented by Chemical Formula 2-1,Chemical Formula 2-2, or Chemical Formula 2-3:R^(a)-L-(CRR)_(n)SM  Chemical Formula 2-1

RRNCSSM  Chemical Formula 2-3 wherein R^(a) includes hydrogen, asubstituted or unsubstituted C1 to C40 alkyl group, a substituted orunsubstituted C2 to C40 alkenyl group, a substituted or unsubstituted C6to C40 aryl group, a C1 to C10 alkoxy group, or —ROR′ (wherein R is asubstituted or unsubstituted C1 to C20 alkylene group and R′ is hydrogenor a C1 to C20 linear or branched alkyl group), R is the same ordifferent, and is each independently hydrogen or a substituted orunsubstituted C1 to C24 alkyl group, n is an integer of 0 to 15, L is adirect bond, a sulfonyl (—S(═O)₂—), carbonyl (—C(═O)—), ether group(—O—), sulfide group (—S—), sulfoxide group (—S(═O)—), ester group(—C(═O)O—), amide group (—C(═O)NR—) (wherein R is hydrogen or a C1 toC10 alkyl group), a substituted or a unsubstituted C1 to C10 alkylene, aC2 to C10 alkenylene, or a combination thereof, and M is hydrogen,lithium, sodium, potassium, or a combination thereof, wherein the firstligand comprises a compound represented by Chemical Formula 1:MA_(n)  Chemical Formula 1 wherein M is Mg, Ca, Zn, Ga, or In, n isdetermined depending on a valency of the M and is an integer of greaterthan or equal to 2, each A is the same or different, and isindependently a C1 to C10 organic group, a halogen, or a combinationthereof, and wherein the first ligand comprises an organic metal salt, ahalogenated metal, a hydrocarbyl metal, a hydrocarbyl metal halide, or acombination thereof.
 20. The quantum dot-polymer composite of claim 19,wherein the polymer matrix comprises a thiol-ene polymer, a(meth)acrylate polymer, a urethane polymer, an epoxy polymer, a vinylpolymer, a silicone polymer, a polymer or a copolymer of a monomercombination comprising at least one of a first monomer comprising acarboxylic acid group and a carbon-carbon double bond, a second monomercomprising a carbon-carbon double bond and a hydrophobic moiety and notcomprising a carboxylic acid group, and a third monomer comprising acarbon-carbon double bond and a hydrophilic moiety and not comprising acarboxylic acid group, or a combination thereof.
 21. A display devicecomprising a plurality of quantum dots, wherein the plurality of quantumdots comprises a quantum dot comprising: a semiconductor nanocrystalparticle; a first ligand bound to a surface of the semiconductornanocrystal particle; and a second ligand bound to the surface of thesemiconductor nanocrystal particle, wherein the second ligand comprisesa compound represented by Chemical Formula 2-1, Chemical Formula 2-2, orChemical Formula 2-3:R^(a)-L-(CRR)_(n)SM  Chemical Formula 2-1

RRNCSSM  Chemical Formula 2-3 wherein R^(a) includes hydrogen, asubstituted or unsubstituted C1 to C40 alkyl group, a substituted orunsubstituted C2 to C40 alkenyl group, a substituted or unsubstituted C6to C40 aryl group, a C1 to C10 alkoxy group, or —ROR′ (wherein R is asubstituted or unsubstituted C1 to C20 alkylene group and R′ is hydrogenor a C1 to C20 linear or branched alkyl group), R is the same ordifferent, and is each independently hydrogen or a substituted orunsubstituted C1 to C24 alkyl group, n is an integer of 0 to 15, L is adirect bond, a sulfonyl (—S(═O)₂—), carbonyl (—C(═O)—), ether group(—O—), sulfide group (—S—), sulfoxide group (—S(═O)—), ester group(—C(═O)O—), amide group (—C(═O)NR—) (wherein R is hydrogen or a C1 toC10 alkyl group), a substituted or a unsubstituted C1 to C10 alkylene, aC2 to C10 alkenylene, or a combination thereof, and M is hydrogen,lithium, sodium, potassium, or a combination thereof, wherein the firstligand comprises a compound represented by Chemical Formula 1:MA_(n)  Chemical Formula 1 wherein M is Mg, Ca, Zn, Ga, or In, n isdetermined depending on a valency of the M and is an integer of greaterthan or equal to 2, each A is the same or different, and isindependently a C1 to C10 organic group, a halogen, or a combinationthereof, and wherein the first ligand comprises an organic metal salt, ahalogenated metal, a hydrocarbyl metal, a hydrocarbyl metal halide, or acombination thereof.
 22. The display device of claim 21, wherein thedisplay device comprises a quantum dot polymer composite and in thequantum dot polymer composite, the plurality of quantum dots aredispersed in a polymer matrix.
 23. The display device of claim 21,wherein the display device comprises a layer comprising the plurality ofquantum dots and the layer comprises at least one of a first patternedlayer that is configured to emit a first light and a second patternedlayer that is configured to emit a second light.